Some researchers believe that there is no doubt _______ a cure for AIDS will be found.
| A．which | B．that | C．what | D．whether |
The woman _____ her boss of having broken the labor law because he fired her when she was pregnant.
| A．blamed | B．charged | C．accused | D．scolded |
The business of the company was growing so fast that the manager had to _____ more workers.
| A．take in | B．take on | C．take up | D．take after |
However, at times this balance in nature is disturbed, ____ a number of possibly unforeseen effects.
| A．lying in | B．calling in | C．existing in | D．resulting in |
China's population is expected to increase to about 1.5 billion in 2040, ______it will start to decline slowly.
| A．where | B．which | C．on which | D．after which |
Catching _____ sight of their head teacher coming, the students fell into silence all of _____ sudden.
| A．the; the | B．/; a | C．the; a | D．/; / |