一般现在时代替过去时

1 )"书上说"，"报纸上说"等。

　 The newspaper says that it's going to be cold tomorrow.

　 报纸上说明天会很冷的。

2) 叙述往事，使其生动。

　 Napoleon's army now advances and the great battle begins

一般现在时代替完成时

1) 有些动词用一般现在时代替完成时：

hear, tell, learn, write , understand, forget, know, find , say,　remember.

　I hear (= have heard) he will go to London.

　I forget (=have forgotten) how old he is.

2) 句型 " It is … since…"代替"It has been … since …"

3) It is (= has been) five years since we last met.

一般现在时代替进行时