Question

By the time he realizes he ____ into a trap, it’ll be too late for him to do anything about it.

A．walks

B．walked

C．has walked

D．had walked

Answer 1

C

句意為：到他意識(shí)到已經(jīng)進(jìn)入一個(gè)圈套的時(shí)候，對(duì)于他來(lái)說(shuō)做任何事情也都為時(shí)已晚了。與by the time 連用的句子應(yīng)該用什么時(shí)態(tài)， 主要是看這個(gè)時(shí)間點(diǎn)發(fā)生在過(guò)去還是現(xiàn)在或?qū)��?lái)。句中he realizes是現(xiàn)在的時(shí)間點(diǎn)，所以要用現(xiàn)在完成時(shí)，如By the time he is ten, he has outgrown his older brother. 他十歲的時(shí)候就已經(jīng)長(zhǎng)得比他哥哥高了。D項(xiàng)一般是從句為一般過(guò)去時(shí)的時(shí)候，主句才用過(guò)去完成時(shí)。