do
一般现在时 I do my homework everyday.我每天做作业(表示经常)
did
一般过去时 I did my homework yesterday.我昨天做作业(表示过去)
does一般现在时第三人称 He does his homework everyday.他每天做作业(第三人称经常)
doing 进行时态 一般和
be动词(am is are was were连用)I am doing my homework now.我正在做作业(进行)
was和were 是is am 和are的
过去式 He is here.(他在这)He was here (他刚刚在这)
are 和 were 同理
还是买本语法书吧,这算是最简单的语法了