81、If I___to do the experiment,I would do it some other way.（）
B．should be going
82、I would not be home tonight___ you not___me a lift in your car.（）
83、We___it without your help.（）
A．couldn't have done
C．could have done
D．could haven't done
84、___in the crash,he won't participate in the race.（）
A．His broken leg
B．His leg is broken
C．His leg having been broken
D．His leg being broken
85、So fast ___that it is difficult for us to imagine its speed.（）
C．does light travel
D．has light traveled
86、Is this film moving?Yes,it is___.（）
A．Rarely have I seen this before.
B．Rarely before have I seen this.
C．Rarely have I seen before this.
D．Rarely I have seen this before.
87、I suppose she is not serious,___?（）
88、I can only do it for you ___I'm paid in advance.（）
D．on condition that
89、Whatever is worth ___ at all is worth ___well.（）
D．being done,being done
90、You'll see to it ___everything is ready in time.（）