since引导一个时间状语从句时,从句何时用一般过去式,何时用现在完成时?? 例如:——Have you known Dr.Jackson for a long time? ------Yes,since he jioned the Chinese Society. since后的句子为什么是一般过去式,而不是现在完成时
1 sinceçæææ¯âä»....çæ¶åå¼å§âï¼ä¸è¬æ åµä¸ï¼é½æ¯ä»è¿å»ææ¶ææ个å¨ä½ç®èµ·ï¼å æ¤ç¨ sinceå¼å¯¼çå¥åé½æ¯ä¸è¬è¿å»æ¶ã 2 ç°å¨å®ææ¶è¡¨ç¤ºâä»è¿å»ææ¶å¼å§å»¶ç»å°ç°å¨çå¨ä½âï¼åsinceå¼å¯¼çä»å¥æé æ£åéã 常ç¨çå¥åç»æå°±æ¯ ç°å¨å®ææ¶+sinceä»å¥ eg I have been here since I was born.
首先, since表示"自从.....以来",表示的动作是从过去以来一直持续到现在,所以since引导的从句要用一般过去时态,但主句只能用现在完成时态,因为现在完成时态表示的动作就是从过去一直持续到现在.如以下句子. I have taught English since 1999. I have lived here since I worked here. He has been here since he joined the army;本回答被提问者和网友采纳
第2个回答 2012-06-08
看例子 1. It has been 3 years since he began to smoke 自从他开始吸烟已经三年了 2. It has been 3 years since he smoked 自从他不吸烟已经三年了 3. It has been 3 years since he has smoked 自从他不吸烟已经三年了 根据例子,since后的句子如果是一般过去时,短暂性动作表示自从做。。。已经。。了如例句1 延续性动作表示 自从不做。。。已经。。。了 如例句2 如果是完成时态,也表示自从不做。。。已经。。。了 如例句3