They _________ on the program for almost one week before I joined them, and now we are still working on it as no good results have come out so far.
#103812
A
have worked
B
had worked
C
have been working
D
had been working
推荐题目
It is believed that a new kind of drug ______ by the scientists and they are hopeful that they will succeed in a few months.
#102623
A
has been developed
B
is being developed
C
is developing
D
has developed
Mary said they _____________________with each other for six years before they got married.
#100282
A
has fallen in love
B
had fallen in love
C
had been in love
D
has been in love
Recently quite a lot of experts have suggested that another law on wildlife protection as soon as possible．
#102999
A
must be passed
B
be passed
C
was passed
D
being passed
When the old man ______ to walk back to his house, the sun ______ itself behind the mountain.
#100109
A
started; had already hidden
B
was starting; hid
C
had started; had already hidden
D
had started; was hiding
Ladies and gentlemen, please fasten your seat belts. The plane ______..
#99022
A
take off
B
is taking off
C
has taken off
D
took off