另学生纠结的英语考点一：It be +时间+when/that/since/before用法辨析
It+be+……+that/since/before/when用法辨析
1.it was+ (时刻，或时间点）+ when sth. happened.当某事发生时，是几点钟或哪一年如：It was 1997 when Hongkong returned to China.
It was five o'clock when we arrived at the small mountain village.
对比强调句型：It was at five o'clock that we arrived at the small mountain village.
It+ is/ was+…+that…多用于强调。
判断方法如下：去掉it、be和that，余下的部分仍是一个完整的句子，这样的句子一定是强调句。
2.it was+一段时间+ before sth happened. 过了一段时间之后，某事才发生了。如：
it was two years before Macao returned to China.
it will be +一段时间before sth. happens.要过一段时间之后，某事才会发生。
或不用过多久，某些就将发生：it won't be long before sth. happens.
It won’t be long before you see him again.
没过多久就…
It was long before they escaped from the prison.
过了很久才….
3.it is (=has been)+一段时间since sth. happened.自某事发生以来，（时间）已经过去。。。了。
如：It is 11 years since Hongkong returned to China.香港回归已经有11年了。
若从句中的动词是终止性动词，意为：“从开始……多久了”例如：
It has been five years since she left home.（她离家已经十五年了）
It was four years since he had died.（到当时为止，他已死去四年了）
It is/has been two days since she fell ill. (她生病两天了）
若从句中的动词是延续性动词，意为：“不做某事已有多久了”例如：
It is two days since she was ill.（她病好了两天）
It is two years since he studied English.（他已有两年没学英语了）
强化习题：
1. It was two years ________he realized the truth.
2. It will be two years ________ the economic situation improves.
3. It was two years later ________ he realized the truth.
4. It is /has been two years ________ he lived here.
5. It was midnight ________ he arrived home.
6. It was at midnight ________ he arrived home.
7. It was not until midnight _______ he arrived home.
A. before
B. when
C. since
D. that
【答案与解析】
1、2两个小题都选A。第一题意为：两年后他才得知真相。第二题意为：经济形式要等两年后才会有所好转。
【归纳】It was/ will be +一段时间+before+句子是高考一个重要考点。意为：多久之后才……要注意：It will be +一段时间+before+句子，before引导的是一个时间状语从句，所以后面的从句要用一般现在时态表将来。
3. D 此题为强调句型。把It was…that去掉后，句子仍然成立：He realized the truth two years later.
4. C 本句意为：他不住在这儿已经两年了。
【归纳】为since意为自从某时或某事发生以来，故since后从句时，从句的时态应用一般过去时态，而主句应用现在完成时态。如表示某某事发生多久了，则用：It is/ has been+一段时间+since+从句。
【注意】It is/ has been+一段时间+since+从句。在本结构中，从句的谓语动词如为延续性动词时，翻译时要从动作结束时算起。
5. B本句为定语从句，先行词为midnight,在从句中作状语。要注意与第6小题的区别，第6题为强调句型，故答案应为that。
6.D 再看下面两题：
(1) It was the park ________ he first met his wife.
(2) It was in this park ________ he first met his wife.
第一题答案应为where,为定语从句；第二题答案为that, 为强调句型。7.D本题亦为强调句型结构：It was not until…that…意为：直到……才……