I have ______ all the papers but I still can’t find my notes．
A．looked for
B．looked through
C．looked after
D．looked out
_____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
