15问答网 > It be+ ... since⼀before⼀when 分别在哪些情况下用？

It be+ ... since⼀before⼀when 分别在哪些情况下用？

It be+ ... since/before/when 分别在哪些情况下用？

2025-02-16 05:50:46

推荐回答（2个）

回答1：

一before.
1.It was/will be+时间段+before... 过了…才…
eg:It was three years before he finished the work.他花了三年才完成这项工作.
It will be three years before he finishes the work.他得花三年才能完成这项工作.
2.It won't be/take long before...不久就会…
eg:It won't be long before he finishes the work.他不久就会完成这项工作.
二since.
1.It is/has been+时间段+since...自从…以来，过了…
eg:It is/has been three years since he finished the work.自从他完成这项工作已经三年了.
2.该句型中若since后跟延续性动词，要翻译成否定含义,即“没做某事已经多久了”.
eg:It has been three years since he worked here.他不在这工作已经三年了.
It has been three years since he smoked.他已经戒烟三年了.
3.若主句非It is…形式，则主句还可用过去完成时.
eg:He had been worrying since the letter arrived.自从接到那封信后他就一直焦虑不安.
三when.
when没有固定与It is…连用的句型.when可表示时间点或时间段，因此从句中短暂性动词或延续性动词均可用.when还可作并列连词，表示突然发生一个动作,等于and at that time.常用句型:
1主语+was/were doing when...
2主语+was/were about to do when...
3主语+had/hadn't done for some time when...
如果还有问题可以PM我，希望能够帮到你～

回答2：

since 自从.
It is cold since winter comes. 自从冬天来了就很冷.
before 在什么之前
It is hot before autumn comes. 秋天来了之前还是很热的.
when 当...之时
It is ten o'clock when the clock strikes ten.当钟敲十下之时,十点了.

具体情况具体分析,it也不是一定只能和这3个词搭配,这3个词也不是一定只能和it搭配.

最新问答

北洋政府时期有哪个将军是给部下枪杀的?

已知ab不等于零，求证a加b等于一的充要条件是a的三次方加b的三次方加ab减a的二次方减b的二次方

艺术摄影如何分类？

海尔3P柜式变频空调KFR-72LW⼀06NAC13一小时几度电? 输入功率：2321 ，制冷量：7200 ，能效比：3.1 。