A new kind of drug ___ ___ to cure H7N9 bird flu by the scientists and they are hopeful that they will succeed in a couple of weeks. 
#100007
A
has been developed
B
is being developed
C
is developing
D
has developed
推荐题目
The telephone _______, but by the time I got indoors, it stopped.
#104961
A
had rung
B
was ringing
C
rings
D
has rung
The mother who lost her son insisted that the careless driver      for the traffic accident ___      yesterday .
#103261
A
was to blame ; happening
B
be to blame ; happened
C
be blamed ; was happened
D
was to blame; had happened