Although the causes of cancer ____we do not yet have any practical way to prevent it.
#105341
A
are being uncovered
B
have been uncovering
C
are uncovering
D
have uncovered
推荐题目
—What's that noise?—Oh，I forgot to tell you.The new machine ________.
#105313
A
was tested
B
will be tested
C
is being tested
D
has been tested
5.---Have you handed in your schoolwork yet? ---Yes，I have. I guess it ____ now.
#105345
A
has graded
B
is graded
C
is being graded
D
is grading
—Believe it or not! I should get my lost wallet back after I left it in the taxi this morning.—Couldn’t agree more! You know, someone _______ it. There are still good persons in Chongqing.
#105322
A
can have taken
B
might have taken
C
should have taken
D
must have taken
New medicines and instruments ______ every day to extend life.
#105334
A
develop
B
are being developed
C
are developing
D
have developed