Japanese verb practice: return a sentence to dictionary form

Why find the dictionary form?

A dictionary normally groups the main entry under the base form. When you meet a conjugated word, identify that verb while retaining the original sentence. The entry gives you a meaning; the sentence tells you how it is used here.

Do not remove endings blindly and assume the remaining letters are an entry. Verb groups and irregular forms matter. Compare a few known examples before trying to state a pattern.

Compare 食べました, 飲みました and 来ました

食べました leads to 食べる（たべる）. 飲みました leads to 飲む（のむ）. 来ました, read きました, leads to 来る（くる）. The changes are not identical, so a single mechanical replacement will fail.

In 昨日、お茶を飲みました。, the past polite form tells you about a completed drinking event yesterday. Looking up 飲む should not make you translate the original sentence as present tense.

Return from the entry to the original sentence

After the lookup, read the original again. Identify the object, time and form. A useful note includes the base word plus the actual form you encountered. This connects vocabulary knowledge to sentence interpretation.

If the apparent base has an unrelated meaning, check the analysis. A spelling match is not enough. A sentence can also contain more than one verb, so decide which word you are trying to explain.

Try a two-direction check

Take three familiar dictionary forms, produce a polite past form, then work back from those forms after a break. Check with reliable reference examples rather than grading a guess from memory.

Change the subjects and objects while keeping the target form. Later, change the form as well. This helps distinguish remembering one complete sentence from understanding what the verb ending contributes.

Try it yourself

Find the dictionary form of 買いました in 昨日、本を買いました。Does the original sentence describe a past purchase?