現(xiàn)在進(jìn)行時(shí)：
肯定句：He's climbing a tree.
疑問(wèn)句：Is he climbing a tree?
否定句：He isn't climbing a tree.
一般過(guò)去時(shí)：
肯定句：He climbed a tree.
疑問(wèn)句：Did he climb a tree?
否定句：He didn't climb a tree.
將來(lái)時(shí)：
肯定句：He's going to climb a tree.
疑問(wèn)句：Is he going to climb a tree?
否定句：He isn't going to climb a tree.
現(xiàn)在完成時(shí)：
肯定句：He's climbed a tree.
疑問(wèn)句：Has he climbed a tree?
否定句：He hasn't climbed a tree.