语言的理解很重要。英语我一直以为很容易的一种语言，不想也有不解的事情发生。以下文字出自Cambridge Advanced Learner’s Dictionary（推荐），仅举三例以说明（部分引用编辑）：
which (ADDS INFORMATION)
used to add extra information to a previous clause, in writing usually after a comma:
Examples: That bar on Milton Street, which by the way is very nice, is owned by Trevor’s brother.
She says it’s Charlotte’s fault, which is rubbish, and that she blames her.
Anyway, that evening, which I’ll tell you more about later, I ended up staying at Rachel’s place.
It’s the third in a sequence of three books, the first of which I really enjoyed.
He showed me round the town, which was very kind of him.
verb learned or UK ALSO learnt, learned or UK ALSO learnt
1 [I or T] to get knowledge or skill in a new subject or activity:
They learn Russian at school.
"Can you drive?" "I’m learning."
I’ve learned a lot about computers since I started work here.
[+ to infinitive] I’m learning to play the piano.
[+ question word + to infinitive] First you’ll learn (how) to use this machine.
3 [I or T] to start to understand that you must change the way you behave:
She’ll have to learn that she can’t have everything she wants.
She soon learnt not to contradict him.
He’s not afraid to learn from his mistakes.
get back to sb phrasal verb
to talk to someone again, usually on the telephone, in order to give them some information or because you were not able to speak to them before:
I’ll get back to you later with those figures.