复合管的穿透电流等于组成它的各三极管穿透电流之和。()
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A．on thatB．on whichC．at thatD．at which
A. on that
B. on which
C. at that
D. at which
—Hello! Can I speak to Alice, please？ —Sorry. She isn’t in at the moment. —______？ Please
A. Could I leave a message
B. Can you hold the line
C. Will you put me through
D. May I take a message
A sound personal health choice is often difficult to make because______.
A. current medical knowledge is still insufficient
B. there are many factors influencing our decisions
C. few people are willing to trade the quality of life for longevity
D. people are usually influenced by the behavior. of their friends
According to Fries and Crapo sound health choices should be based on______.
A. personal decisions
B. laws of society
C. statistical evidence
D. opinions of friends
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