If a healthy environment is gone, ________ everything that our life depends on.
A．so is B．nor is
C．so does D．nor does
—Under no circumstances ________ the door to the Data Centre unlocked.
—I promise I'll be more careful in future.
A．you need to leave B．should you leave
C．need you leave D．you should leave
The drug used to treat this disease causes bad side effects, some of which ________ deadly.
A．is B．are
C．was D．were
．No sooner ________ down on bed ________ the telephone rang.
A．had he lain; than B．had he lied; when
C．did he lie; than D．had he laid; before
________ about wild plants that they decided to make a trip to Madagascar for further research.
A．So curious the couple were
B．So curious were the couple
C．How curious the couple were
D．The couple were such curious
Fighting an artificial greenhouse effect seems to be the greatest of environmental challenges, ________？
A．isn't it B．does it
C．doesn't it D．is it
