We _______ on it for several hours but we have not yet reached any conclusion.
#104695
A
work
B
areworking
C
havebeenworking
D
havebeenworked
推荐题目
The library needs ________, but it’ll have to wait until Sunday.
#104295
A
cleaning
B
be cleaned
C
clean
D
being cleaned
Although the Eiffel Tower ________ to last for 20 years, it is still standing today.
#99837
A
has designed
B
had designed
C
is designed
D
was designed
—What’s that terrible noise? —The neighbors ________ for a party. 
#104750
A
have prepared
B
are preparing
C
prepare
D
will prepare