选哪个，为什么选？麻烦讲解一下，谢谢！
Absorbed in reading a book on the bus, he had his wallet (
).
A: stealing b:to steal
c:have been stolen d:stolen
You need to ( ) before posting it.
A: have the letter stamping b:have the leter to stamp
C:have the letter stamped
d:be stamped tour letter
I remember ( ) somewhere in the past.
A:to meet himb:meet him c:having met himd:to have been met
Your window wants （）; you had better have it
this week.
A:cleaingdo b:to be cleaned do c:cleaning done d:being cleaned
done
They tried every way possible （） the child, but it was too late.
A:saving b:to save c:to have saved d:to be saving
The concert began before we （ ）.
A:were seatingb:seated c:were being seatedd:were seated
Gradually she （ ） to see the meaning of his words.
A:becameb:has become c:came d:has to come
Anyone carrying guns was prohibited （） the building.
A:to enterb:enteringc:from enteringd:not to enter
During the entrance examination, the examiner had the examinees （ ）apart from each other.
A:to sit b:sitting c:sit
d:to have sat
This is a nation which（ ）easily to changes.
A:adaptsb:is adaptedc:is adaptable d:is adapting
We are happy to see millions on the earth who have nothing but a record of misery and hunger ( ) to improve their life.
A: to have the chanceb:having the chancec:have the chanced:who have the chance
DCCCBDACCAD1、had something done2、同13、remember doing记得做过某事，in the past表明是完成时4、something need\want doing=something need\want to be done，后面一空同15、表目的6、表被动7、gradually逐
