If and when the implementing legislation is crafted, then Congress canvote to approve or disapprove the deal, but can’t change or amend it.疑问：查了下字典把 if and when 翻译成“如果”，那么这个和一般的 if 有何差异？
在网上看到这么一句话：表达认为某事极有可能的观点，这是出于说话人已知的观点或常理性期待而做出的合乎逻辑的结论：Her mega hairdo must have taken several cans of hairspray to achieve.请问：为什么要用must have done这种形式？
No matter how frequently ______, the works of Beethoven always attract large audiences.A.performing B.performed C.to be performed D.being performed请老师详细讲解这道题，谢谢老师!
A year and half later, my grandfather became gravely ill. When he returned from several weeks in the hospital, he wanted his bed next to the window, where he could see his beloved rosebush.from 加weeks是什么意思？还有in从医院里回来吗？
... in invasion and expansion. Instead / However we have the confidence to conquer all forms of invasion .“ Xi told government leaders and current and retired PLA members.这个句子里用 instead 好还是 however 好。
______,Thoms Edison invented a device to transmit a special signal while he slept.A. he was a night telegraoh operator B. That he was a night telegraphe operatorC. As a night telegraph operator D. whereas a night telegraoh operator这道题独立结构，选择C应该没有错误的...
She gave up the only form of soft power at her disposal, given her inability to make people feel at ease, which was trust that she would do the right thing.老师好，定语从句里which先行词是谁？后面的that引导的是什么句子？
There ought to be less anxiety over the perceived risk of mountain climbing than exists in the public mind today. 本句翻译是：对于可察觉到的登山的风险，目前公众心中所存在的疑虑过多。请问前面写了 the less anxiety 不是更少的焦虑吗，为什么翻译...
You'd better see Dr Wang about that cough.Did he often come to the hospital on consultations?...Nina,you should have faith in doctors ,especially in DR Wang,he is a very experienced expert....我不太理解这组对话中，那几个介词短语的作用，想请老师讲解以下,谢谢