问题 when, as, while, since的区别

_____ Tom waited for the exam result, he became less and less patient.  A. When    B. As      C. While   D. Since 答案为 B。请解释一下 when 与 as 的区别，谢谢！

问题 对since和for提问是用when还是how long

—When did you come here?—______________.A. Half an hour beforeB. Since half an hourC. Half an hour agoD. For half an hour①请问这道题选A还是C呢？这两个选项又有什么区别呢？②对since和for提问是用when还是how long？

问题 since与after引导从句时的区别

_______ I finished there,I have been working for a travel agency in my country organizing tours and excursions for tourists from all over the world. 横线上可以用 After 吗？答案是 Since。

问题 since, because, as 在原因状语从句中是什么词性

原因状语从句中的引导词since, because, as 在原因状语从句中是什么词性，是修饰整个从句的副词吗？

问题 since being split from 是介词+动名词宾语的结构吗

News corporation made its biggest acquisition since being split from the film and television parts of Rupert Murdoch's empire, by agreeing to buy Move, an online property listings firm, for $950m.请问老师，句中的since being split from 是介词+动名词宾语的结构吗？谢谢！

问题 短语中的since the 1930s做什么句子成分？

A center of heavy industry in China since the 1930s划线部分是什么句子成分？是定语吗，还是状语，还是无动词分句？谢谢老师回答。

问题 day one, from day one, since day的区别

day one, from day one, since day 都表示从第一天起，它们的区别是什么？

问题 since和when表原因的区别

How silly  it is to travel out by high-speed rail _____you can take a plane,whichis much cheaper.A.while    B.when    C.since    D.though答案选B，可是C有既然的意思也能说通为什么不选？

问题 ​since he lived in New York 究竟何意

since he lived in New York究竟是自从他住在纽约以来，还是自从他离开纽约以来呢？ 不同的语法书有不同的说法，好糊涂。

问题 since this year 的说法有错误吗

问题 while与since的用法与理解

这里的while翻译成什么好，我觉得写成since更合适：Archaeologists find that even the most isolated residences during the eleventh and twelfth centuries obtained some pottery, and probably food, from some distance away, while major ceremonial events were opportunities for sharing food...

问题 since后接延续动词一般体和完成体的语意理解

对句型"It is/has been +段时间+since+延续动词一般体/完成体"表达语意的疑问：1.It's been three years since I worked in this company.2.It's been three years since I have worked in this company.我手头的语法书有两种对立观点，第一种认为，在此句型中，无论...

话题 非延续性动词的否定形式和since 连用

问题 It has been three months since we had winter vacation的理解

老师好！在理解句子It has been three months since we had winter vacation的时候我遇到问题：have winter vacation这个动词短语的动词have是非延续动词还是延续性动词？如果have在这里是非延续性动词，It has been three months since we had winter vacation是...

问题 after that,since then 自那以后，区别