Vocabulary practice · Skill 12 of 14

Word Forms Exercises: Noun, Verb, Adjective and Adverb

Word forms are the members of one word family: decide, decision, decisive, decisively. Students usually know the family but pick the wrong member, such as explosion where the sentence needs explosive. The fix is to read the slot first: what part of speech does this place need? Then choose the ending. Seven rules and 40 questions below show you how.

40 questions 8 levels of 5 7 rules Level 1 free

1 in 4

What we measured

of the 40,853 Complete the Words boxes students missed in 12,000 of our Reading sections started right and ended wrong, such as explosion where the sentence needed explosive.

How do you choose the right word form?

Read the slot before you choose the word

This one habit fixes more word-form mistakes than any other. Before you think about endings, ask what job the empty place in the sentence needs. After a, the, my or an adjective, you need a noun. Between an article and a noun, or after is or seems, you need an adjective. To describe a verb, you need an adverb. After to, can or will, you need the base verb. Only then choose the ending.

Right:We made a decision.
Right:It was a decisive moment.
Right:She answered decisively.
Right:We need to decide today.

Not:It was a loud, explosion sound.Instead:It was a loud, explosive sound.
Not:Local farms product most of our rice.Instead:Local farms produce most of our rice.

Adjective endings: -ive, -ous, -ful, -less, -al, -ic, -able

Adjectives describe nouns, and many show it with their ending: -ive (explosive, productive), -ous (dangerous), -ful and -less (colorful, countless), -al (natural), -ic (atmospheric), -able (remarkable) and -ory (migratory). When the slot sits between a or the and a noun, or after very, check that your word has one of these. Watch the pairs that share a start: countable means you can count it, while countless means too many to count.

Right:The festival had colorful costumes.
Right:It was a very productive meeting.
Right:The museum has countless old maps.

Not:Her speech was very emotion.Instead:Her speech was very emotional.
Not:Whales are migration animals.Instead:Whales are migratory animals.

Noun endings for things and ideas

A noun names a thing, an action or an idea. It fills the slot after a, the, my or an adjective, and before of. Common noun endings are -tion and -sion (production, decision), -ment (improvement), -ness (kindness), -ity (activity, salinity) and -ance or -ence (importance, difference). A few nouns end in -al, such as survival and arrival. Nouns in -ance and -ence usually have an adjective partner in -ant and -ent: important, different.

Right:The survival of the plant depends on rain.
Right:We noticed a big improvement.
Right:Salinity is the amount of salt in water.

Not:Her arrive was a surprise.Instead:Her arrival was a surprise.
Not:The important of sleep is clear.Instead:The importance of sleep is clear.

Verb endings and base verbs

A verb is the action, and many verbs have no special ending at all: produce, decide, survive, migrate, endure. Others are built with an ending that means make or become: -ize (organize), -ify (simplify), -en (widen) and -ate (activate). Use the plain base verb after to and after can, will, should and must. A noun such as product or activity cannot be the action of a sentence.

Right:Many birds migrate in the fall.
Right:We need to simplify the plan.
Right:Few plants can endure such heat.

Not:The machine can product 200 bottles an hour.Instead:The machine can produce 200 bottles an hour.
Not:This switch will activity the lights.Instead:This switch will activate the lights.

Adverbs: -ly, -ically and the linking-verb trap

Adverbs describe verbs, adjectives and other adverbs, and most are an adjective plus -ly: decisive, decisively. Adjectives ending in -ic add -ally: scientific, scientifically; dramatic, dramatically. One trap catches even strong students. After be, seem, become, look and feel, the word describes the subject, not an action, so it stays an adjective. The result was remarkable, not remarkably.

Right:Prices rose dramatically last year.
Right:The change was remarkable.
Right:The results were scientifically sound.

Not:He drives very careful.Instead:He drives very carefully.
Not:The view from the hill was remarkably.Instead:The view from the hill was remarkable.

People, fields and descriptions

Many families have one member for the field, one for the person and one for the description. Science is the field, a scientist is the person, and scientific describes things: a scientific method. People nouns usually end in -ist, -er, -or or -ian: biologist, researcher, editor, musician. When the slot does an action, as in a person who studies or scientists found, it needs a person. Adjectives never take a plural -s, so scientifics is never right.

Right:Scientists found a new kind of frog.
Right:She is a biologist.
Right:It was a scientific study.

Not:Many scientific agree.Instead:Many scientists agree.
Not:My aunt is an economy at a bank.Instead:My aunt is an economist at a bank.

Count the things: plurals inside a word family

Inside one family, some nouns are uncountable and some are countable. Nutrition, the process of feeding, is uncountable, but nutrients are the countable things in food. Production is a process; products are the things it makes. Creation is the act of making; creatures are living things you can count. When the slot follows many, several, two or these, or comes before a plural verb, choose the countable member and add -s.

Right:Beans are full of nutrients.
Right:The reef is home to many creatures.
Right:The store sells local products.

Not:Fruit contains many nutritions.Instead:Fruit contains many nutrients.
Not:We saw several strange creations in the pond.Instead:We saw several strange creatures in the pond.

Where this costs you marks on the TOEFL

The TOEFL iBT has no separate grammar section, so word forms cost marks inside other tasks. The clearest place is Reading, which has 50 items, including the Complete the Words boxes: you see the first half of a word and type the rest. A box with the right start and the wrong ending, such as product where the sentence needs produce, is still a missed box, so read the whole sentence before you type. In Writing, a slip such as "a very success plan" in your email or academic discussion post makes your language control look weaker, and the same slips make your Interview answers sound less precise. To train the Reading habit, try our Complete the Words practice.

If your first language is...

First language	What to watch for
Chinese, Vietnamese and Thai speakers	Words in these languages do not change their endings, so the job of a word is shown by its position or by a separate small word. That is good training for reading the slot. English adds one step: once the position tells you the job, the ending has to match it, as in decide, decision and decisive.
Spanish and French speakers	Many endings map neatly: Spanish -ción and French -tion become English -tion, and -ivo and -if become -ive. One gap causes a common slip. Científico and scientifique can mean both scientific and a scientist, so "the scientifics" feels natural. English splits them: scientist is the person, scientific describes things. Also watch -ment: in French it often makes adverbs, as in rapidement, but in English it makes nouns, as in improvement.
German and Dutch speakers	German and Dutch use the same form for an adjective and its adverb: schnell and snel mean both quick and quickly. That is why "she explained it very clear" can sound fine to you. In English, a word that describes how an action is done usually needs -ly, so check each word that describes a verb.
Arabic speakers	Arabic builds word families from a root, usually three consonants, and changes the pattern around it to show the job: k-t-b gives kataba (he wrote), kitab (book) and katib (writer). You already think in families. English marks the job mostly at the end of the word, so train your eye on the last few letters.

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Word forms exercises: Level 1 with answers

Try these before you open an answer. Each one explains why, not only what.

The professor gave a clear _____ of the homework. (explain / explanation / explanatory)
Show the answer
explanation
After a clear, the sentence needs a noun, the name of the thing the professor gave. Explain is the verb and explanatory is an adjective, so only explanation fits.
There has been a big _____ in my English this year. (improve / improvement / improved)
Show the answer
improvement
After a big, the slot needs a noun. The ending -ment turns the verb improve into the noun improvement, the change that happened to my English.
Find the mistake: Thank you for your kind during my first week.
Show the answer
Thank you for your kindness during my first week.
After your, the slot needs a noun, the thing you are thanking someone for. Kind is an adjective; adding -ness gives the noun kindness.
Your _____ is due on Monday. (apply)
Show the answer
application
After your, you need a noun, and is shows it is one thing. The ending -tion (here -ation) turns the verb apply into the noun application.
Complete the word: After a long talk with her advisor, Mia made a final deci____.
Show the answer
decision
After a final, the slot needs a noun. Decisive has the same start and the same length, but it is an adjective, and deciding is a verb form, so only decision fits.

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FAQ

Common questions

What are word forms?

Word forms are the members of one word family, such as decide, decision, decisive and decisively. They share a start, and the ending usually shows the part of speech: verb, noun, adjective or adverb. Choosing the right form means matching the word to its job in the sentence, which is why reading the slot always comes first.

How do I know if a word should be a noun or an adjective?

Look at its neighbors. A noun usually follows a, the, my or an adjective, and it can be the subject of a verb. An adjective describes a noun, so it sits right before one, or after be, seem or become. In "a productive meeting", productive describes and meeting is the noun. Ask what the word is doing, then choose the ending that does that job.

What are the most common noun suffixes?

For academic English, the most useful are -tion and -sion (information, decision), -ment (development), -ness (awareness), -ity (activity), and -ance or -ence (importance, difference). For people, look for -er, -or, -ist and -ian: teacher, editor, scientist, musician. A word with one of these endings is usually a noun, which makes a missing-letter box much faster to solve.

What are the most common adjective suffixes?

Look for -ive (creative), -ous (famous), -ful (useful), -less (careless), -al (national), -ic (economic), -able or -ible (reliable, visible) and -ory (migratory). Many adjectives also end in -ant or -ent, the partners of -ance and -ence nouns: important, different. A few endings work both ways, such as -al in the noun survival, so let the slot have the final say.

Do word form mistakes lower my TOEFL score?

They can, in more than one place. In Reading, a Complete the Words box with the right start and the wrong ending counts as a miss. In Writing and Speaking, grammar counts inside your response, so a steady pattern of slips such as "very success" makes your English look less controlled. Reading the slot before you write the ending fixes most of them.

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