. Sales of CDs have greatly increased since the early 1990s, when people ________ to enjoy the advantages of this new technology. 
#104797
A
begin
B
began
C
have begun
D
had begun
推荐题目
--- What is that wonderful smell? --- Our neighbor ________ for a party.
#99373
A
have prepared
B
is preparing
C
prepare
D
will prepare
By the 1920s, Howard Carter ____ an explorer.
#99036
A
has become
B
had become
C
became
D
would become
—You haven’t got the textbook for my chemistry yet.—I know, and we ________ to get it for the last five weeks.
#100488
A
will have been trying
B
have been trying
C
will be trying
D
had tried