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更多“化学需氧量（Chemical Oxygen Demand) …”相关的问题
(Those of us) who work in chemical (laboratories) should have (their) lungs (checked) quite regularly.
A．Those of us
B．laboratories
C．their
D．checked
Reagan offered a Chemical Weapons Treaty,but he ______ to resume bilateral (双方的)talks,which might speed agreement.
A.rejected
B.resolved
C.promised
D.declined
The use of sinking and dispersing chemical agents for removal of surface oil is ______.
A.the most common method used in the United States
B.too expensive for common use
C.generally safe to sea life
D.authorized only with prior approval of the Federal On-Scene Coordinator
Our school-run factory _____ various kinds of chemical devices last year.
A.turned into
B.turned up
C.turned out
D.turned off
We can separate the mixture into the pure chemical compounds______it is composed.
A．in which
B．of that
C．of which
D．from which
