你指的是for sb.to do sth.中的“to do"的时态吧?
一般情况下,这个动作如果发生在谓语动词之前,就用to have done;r如果同时发生就用to be doing,;假如发生在谓语动作之后,就用to do
例如：
He pretended to be sleeping
He pretended to leave the house alone.
He pretended to have finished his work.
你指的是for sb.to do sth.中的“to do"的时态吧?
一般情况下,这个动作如果发生在谓语动词之前,就用to have done;r如果同时发生就用to be doing,;假如发生在谓语动作之后,就用to do
例如：
He pretended to be sleeping
He pretended to leave the house alone.
He pretended to have finished his work.