一、句型介紹

　　這是兩個(gè)很常用的虛擬語(yǔ)氣句型，其意為若不是(有)、要不是有。如：

　　If it werent for water, no plant could grow. 要是沒有水植物就無(wú)法生長(zhǎng)。

　　If it hadnt been for the doctor, he would have died. 要不是醫(yī)生救了他，他就會(huì)死了。

　　二、用法說(shuō)明

　　(1) 此句型有時(shí)可用but for, without等替換。如：

　　If it hadnt been for [But for, Without] your assistance we wouldnt have succeeded. 要不是有你幫忙，我們是不會(huì)成功的。

　　(2) 原則上說(shuō)，if it werent [wasnt] for 用于談?wù)摤F(xiàn)在的情況，而if it hadnt been for 用于談?wù)撨^去的情況。但實(shí)際上if it werent [wasnt] for有時(shí)也可用于談?wù)撨^去的情況。如：

　　If it were not for their help, we couldnt have got over the difficulties. 要不是他們幫助，這些困難我們是克服不了的。