Question

问一些高中英语问题，希望详细解答，谢谢！

1. It is necessary that a college student should master at least a foreign language.为什么用 should master 不用masters？
2. Whoever has helped to save the drowning girl is worth praising.为什么用whoever 不能用 The one？
3. I don't doubt that he will come.为什么用that不能用whether?
4. After what seemed like hours he came out with a bitter smile.这句话什么意思
5. She looked quite different from what she used to be.为什么用what不用who？
6. I want to be liked and loved for what I am inside.为什么不能用how？
7. It is by no means clear what the president can do to end the strike.为什么what不能用that替换，不能说can do to sth.吗?
8. It is not always easy for the public to see what use a new invention can be of to human life.这句话什么意思，还有what有什么作用
9. She may have missed the train, in which case, she won't arrive for another hour.为什么用in which，不用in that？
10. A lot of language learning, as has been discovered, is happening in the first year of life, so parents should talk much to their children during that period.为什么用as 不能用it或者which？

Answer 1

1、should表示需要完成的事情，而不是普遍需要掌握的
2、whoever是强调了who 也可以使用who而who就与the one类似，你懂得、、、
3、因为是不怀疑的句子所以他是否来时肯定的回答，这是固定搭配要记得！！
4、过了好像有几个小时他出来了带着苦笑。
5、无法解释，固定搭配
6、我的内心里的是 什么东西，不是怎么！！！
7、what president can do 是一个句子里的成分。用that就不能做主语或宾语。
8、对于公众来说不容易懂得一个新发明能够给人类带来什么作用。
9、in 是介词连which case，which是指这句话之前的事情，非限制性定语从句 只用which 你没认真看which 和that的使用规则哦。
10、which 也可以、、

Answer 2

it is necessary /strange/important... that 后面用虚拟语气，动词构成 should +do

Answer 3

不知道