在状语从句中现在时表将来时,现在完成时表将来完成时。
例如在两个例子中
1.By the time he retires,Stewart will have worked in this company for more than thirty years. 在这个句子中可以用has worked吗?
2.Ask her to come and see me when she has finished her work.
在从句中要用一般现在时或者现在完成时表示一般将来时或者将来完成时,但是,在主句中,应该用一般将来时或者将来完成时,不能用现在完成时代替将来完成时。