Until the start of the Industrial Revolution, mankind was poor, hungry, and constantly at the _______ of disease and natural disasters．
| A．power | B．limit | C．control | D．mercy |
_____in the sports world，a sportsman needs to train constantly to keep himself in best condition．
| A．Survive | B．Surviving |
| C．To survive | D．Survived |
Teenagers ________ their health because they play computer games too much．
| A．have damaged | B．are damaging |
| C．damaged | D．will damage |
Peter’ shirt looked just the same as Tom’s，but it cost ______ his．
| A．as much twice as | B．twice as much as |
| C．much as twice as | D．as twice much as |
We can’t figure out ______ quite a number of insects and birds are dying out．
| A．that | B．as | C．why | D．when |
______ environmental damage is done，it takes many years for the ecosystem to recover．
| A．Even if | B．If only |
| C．As if | D．Once |