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
