英文 (什麼時候使用??)

is
解釋:put it after he/she/it/there
例句:There is a boy.
例句:He is a boy.

are
解釋:put it after I/we/you/they/there

was
解釋:past tense of 'is'
例句:I was a fireman three years ago

were
解釋:past tense of 'are'
例句:They were having a party yesterday.

shall
解釋:use in future tense;use in suggestions.
例句:Shall we shopping tomorrow?

should:
解釋:應該
Don't change the verb after it.
例句:We should be quiet in the library.

can:
解釋:可以
Don't change the verb after it.
例句:He is strong so he can throw a heavy stone.

could
解釋:past tense of can

have
解釋:有/已經(present perfect tense),if the subject is I/we/you/they
例句:They have a Christmas tree.
例句:We have done our model.

has
解釋:use in simple present tense/present perfect tense,if the subject is he/she/it
例句:She has a son.
例句:He has done her homework.

had
解釋:past tense of 'have'

would
解釋:past tense of 'will'