The Japanese tenses
When something happens and how it is seen — finished, in progress, already done before: that is the question every tense answers. Here are all the topics about it, each with its own page and its own exercises.
All 13 topics on tense and time
N5The ます-formThe polite form of every verb, for habits, for now and for the future.N5Past, suggestions and invitations in ますChange the end of ます to talk about the past, to suggest and to invite.N4The plain pastThe te-form with た in place of て — the casual past, and the base of a whole family of patterns.N5ている: in progress, or the state that remainsている describes an action going on now, or the state that a finished change has left behind.N4てある: left that way on purposeてある describes a state that somebody brought about deliberately, usually as a preparation.N4ておく: doing something in advanceておく means doing something now so that it is ready later — or leaving something as it is.N3ばかり: only just, and nothing butAfter the た-form ばかり means "only just"; after a noun or a て-form it means "nothing but".N3ところ: a point in the life of an actionところ pins an action to one moment: just before it, in the middle of it, or just after it.N4When: とき and the tense inside itとき is a noun meaning "time"; the tense in front of it says before or after, not past or present.N4Intentions and plans: つもり and よていつもり states what a person intends to do; よてい states what has been arranged.N5でしょう and だろう: probablyA plain form plus でしょう: the speaker thinks it is probably so.N4たら: if and when, the all-purpose conditionalThe plain past plus ら: once A has happened, B.N4The ば-form: what it takesA conjugated form that puts the weight on the condition: if A, then B.
Practise the tenses
Exercises from every topic on tense and time, mixed together. That is exactly the hard part: almost anyone can build a form when it says next to it which one is meant.