選擇D
譯為“要不是有他們的幫助,我們就不會(huì)及時(shí)完成這項(xiàng)工程.”
這是對(duì)過去的虛擬,表示與過去的事實(shí)相反的假設(shè)時(shí),條件狀語從句的謂語動(dòng)詞用“had+過去分詞”,主句中的謂語動(dòng)詞用“would(should,could,might)+have+過去分詞” 例如：
If you had taken my advice,you wouldn’t have failed in the examination.
補(bǔ)充：
1.表示與現(xiàn)在事實(shí)相反的假設(shè)時(shí),條件狀語從句中的謂語動(dòng)詞用“過去式（be的過去式用were）”.而主句中的謂語動(dòng)詞用“would(should,could,might)+動(dòng)詞原形” .例如：If he had time,he would attend the meeting.
2、表示與將來事實(shí)相反的假設(shè)時(shí),條件從句和主句所用的謂語動(dòng)詞 與“表示與現(xiàn)在事實(shí)相反的假設(shè)”的謂語動(dòng)詞相同,或者條件從句中用“were to (should)+動(dòng)詞原形”,例如：
If it were to rain tomorrow,the meeting would be put off.
3.當(dāng)條件狀語從句表示的行為和主句表示的行為所發(fā)生的時(shí)間不一致時(shí),動(dòng)詞的形式要依據(jù)它所表示的時(shí)間來調(diào)整.
理解方法：
條件狀語從句比說話者的語言所指的時(shí)態(tài)晚一個(gè)時(shí)態(tài),主句時(shí)態(tài)根據(jù)條件狀語從句時(shí)態(tài)來定,就是在條件狀語從句時(shí)態(tài)條件下加上would(should,could,might),但是動(dòng)詞或助動(dòng)詞遇到would(should,could,might)就要變回原形.
希望能對(duì)你有所幫助.