If it were not for… If it had not been for … but for… 有什么关系和区别,请高手详细讲解,谢谢

If it had not been for与If it were not for有什么区别? Were it not for If it were not for… If it had not been for … but for… 有什么关系和区别,请高手详细讲解,谢谢 ------------for the heavy rain.i should have been here earlier A if it were not B were it notC had it not been D if it wasn't _____ the clouds ,you would find the airplane in the sky easily.A Had it not been for B If it were not C If it had not been for D Were it not for选什么?为什么? if it were not for protection we get from insect-eating animal是什么意思 ()for the snow yesterday ,we would have gone to climb the mountain.a,if it were not b.had it not been c.if it was not d.were it not 求详解语法句式 ____ the sun,nothing could live on the earth.A.Were it for B.Were it not forC.It were for D.If it is not for请说明原因, If it _ for the rain,we _ the picnic yesterday.A were not; could have hadB were not; could haveC had not been; could have had _____ the expense,I _____ to Italy.A.If it were not,go B.Were it not for,would go C.We ______ his advice,we'd better have been cheated.A.If you don't give us B.Had it not been for C.If it were not for D.Should it not for 英语语法：____ the expense,I ____ a round-the-world tour.A.Were it not … would take B.If it were not… takeC.Weren't it for… will take D.If it hadn't been for… would have taken If it were not for their support,we would be in a diffcult situation那个were为什么不是were,而不是 is 或was或 are if it were not for my father,my life would not have been so enjoyable.后半部分求分析 还有前面为什么用were? If it were not for the fact that he ________ ill ,he would finish it.A.is B.be C.were D.am If it were not that...But that he came to help me ,I could not have succeeded .是不是可以改写成:If it were not that he came to help me ,I could not have succeeded .或者改成If it were not for the fact that he came to help me ,I could not h If it were not for the fact that Anne___ill,I would invite her to the show. 要用is?表事实? In the work efficiency of the dormitory always very low,so if it were not for time only urgent,I