waguwk.com 
1.n./adj./adv./v.+as+主语+v.=Although/though+状从Child as he is,he knows a lot.=Though he is a child,he knows a lot.Rich as he is,he never spends a penny on books=Although he is rich,~2.强调：
he came here.=he did come here.
it was (not) ...who/that...
it was not until...that...
eg:
He taught us English in our school last year.It was he that/who taught us English...It was English that he taught us...
It was us that he taught English...
What was it that he taught you ...?
Where was he taught us English...?
When was it that he taught you English...?
It was not until 11 p.m.that I went to bed.It was not until my mum came back that I did the homework.He who likes English is good at ball.
It is he who likes English that is good at ball.*不能连用：because/since/as/for，though/although
