Bythetimeherealizeshe

问题详情：

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

【回答】

C　[由句中realizes及it'll be可知应用现在的时态，故排除B、D两项，由句意可知空白处强调已经完成的动作，故用现在完成时。]

知识点：现在完成时及其被动式

题型：选择题