1):This is all ____I konw about the matter.

1):This is all ____I konw about the matter.
A:that B:what C:who D:whether
2):Do you still remember the day ____we first met?
A:that B:on that C:where D:when
3):I have no idea about the man ____wrote the article.
A:which B:whom C:who D:he
4):They are taking care of the patient ____doctors just performed an operation.
A:on who B:on whom C:who D:whom
5):Do you know the name of the boy_____sister is your classmate?
A:whose B:who C:that D:which
6):It is my fault____could not be forgiven.
A:who B:which C:it D:is
7):John asked Mary if it was the place___she bought the gift.
A:what B:that C:which D:where
8):This is the book_____you were looking for yesterday.
A:who B:where C:/ D:when
9):You didn't tell me the reason___he was so happy.
A:when B:where C:why D:who
10):It rained heavily yesterday,________prevented me from going to the shop.
A:that B:which C:who D:when
(说下选择该项的理由,）