More of us are using headphones in noisier environments, ______ we may turn up the volume to potentially dangerous levels.
A. when B. while C. before D. where
Commercial and recreational fishing ______ population sizes and also made individuals smaller, since big fish ______ and smaller ones thrown back.
A. decreased; kept B. had decreased; are kept
C. has decreased; keep D. has decreased; are kept
— How did you do in the test?
— Just ok. It ______ worse!
A. could have been B. could be C. would have been D. might be
Today scientists describe the universe ______ two basic partial theories—the general theory of relativity and quantum mechanics(量子理论).
A. in terms of B. in memory of C. in favor of D. in honor of
After years of wondering how the idle rich got even richer, we cracked the millionaire’s code, ______ secret is simple: Don’t spend a penny if you don’t have to.
A. which B. that C. whose D. what
Pollution has already destroyed much of the Earth. Only by changing ______ we live can we save our planet.
A. where B. how C. what D. why
