since this semester began ,we have had four tests.为什么从句是一般过去式,主句是现在完成时.

since this semester began ,we have had four tests.为什么从句是一般过去式,主句是现在完成时. This is a very busy semester. 英语翻译原句：Usually it’d be at least ten people,but since it was cancelled this semester,they might even do it with less.这里面,they might even do it with less 英语翻译本学期第一天起,我经常在图书馆学习英语.since the first day of this semester,I often study English in library.请问这句话翻译的对吗?since之后可以用动词一般现在时吗?还是必须用Have done?since the f 英语翻译Have you seen Tom at all this semester? I _______ (make a decision) to study hard this semester. you took an optional course this semester.请翻译一下, i will not procrastinate this semester什么意思 My plan for this new semester 什么意思? Have you seen Tom at all this semester?中的at What if I get in shape this semester?(改为同义句)____ ____ ____ I get in shape this semester?只填这三个空, 翻译Since when was this 根据汉语意思,补全英语句子这家店已经开了五年的时间了 The shop ( ) ( ) ( ) for five years他这一学期以来已经取得了非常大的进步 he ( ) ( ) much ( ) since this semester我的父母总是鼓励我去尝试新的 I had a really hard time ____(study) science this semester. I had a really hard time to science this semester.改错句 i still have 2 credits to fulfill my total credits of this semester.3772 帮忙翻译下句子吧:What papers do have this semester You and I have this semester,it is no return ticket 求翻译