When filled with a gas______ lighter than air, a balloon becomes buoyant and rises.
A．much
B．more
C．less
D．little

未分类题Since his paper contains______ mistakes than ours, his will be entered in the contest.A．lessB．the lessC．fewerD．the fewer

未分类题George appears______a hard time convincing his employer that he is right over it.A．havingB．to be havingC．to haveD．having had

未分类题It is reported that by the end of next month the output of personal computers in the factory______by 10%.A．will be risingB．will have risenC．has risenD．has been rising

未分类题______the beginning of the nineteenth century that the creation of more universities was seen to be either necessary or desirable.A．It was untilB．It was not untilC．Not it wasD．It was from

未分类题In recent years there has been a very rapid increase in the numbers of young people, especially girls, ______higher education.A．seekB．seekingC．soughtD．to seek