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.