it have been necessary 和 it is necessary 的区别?请问下句中it had bee

来源：学生作业帮编辑：作业帮分类：英语作业时间：2024/05/05 09:27:10

it have been necessary 和 it is necessary 的区别?请问下句中it had been necessary用现在时为何不行?
But rich planterswere few in the young county of Clayton,and,inorder to muster a full-strength troop,it had been necessary to raise more recruitsamong the sons of small farmers,hunters in the backwoods,swamp trappers,Crackersand,in a very few cases,even poor whites,if they were above the average oftheir class.

首先,这个故事讲的是过去的事情,所以be肯定不能用现在时,而必须用过去时.其次,如果用与陈述语态相同的时态,表示其发生（或出现）的时间与陈述语态所发生的时间大致相同（从语法角度考虑,此处是可以用过去时was的）；如果用过去完成时态,表示其发生（或出现）的时间比陈述语态所发生的时间更早,也就是相当于汉语的“早就需要...”.
再问：经你一说我感觉明白了。 it had been necessary to raise......和if they were above the average of their class.不是所说的虚拟语气吧，曾有人告诉我说是虚拟语气。
再答：此处不是虚拟语态。

it have been necessary 和 it is necessary 的区别?请问下句中it had bee 求find it necessary和lt is necessary的解释 it is necessary . It is necessary to do 的例句 i feel it necessary 的句子成分分析下为啥不是 it is necessary if it is necessary /if necessary /when it is necessary 意思一样吗 It is necessary for me to have some help 翻译 No ___(far) discussion is necessary.We have decided it. when it is necessary 为什么可以变为when necessary? Is it necessary to learn grammer 英语语法问题 it is necessary that It is necessary that he (take) _take__some