______是一类能与GTP或GDP结合并具有GTP酶活性的膜蛋白。
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非弹性阻力包括呼吸道阻力、______和组织的黏滞阻力。
Passage One Questions 26 to 29 are based on the passage you have just heard.
A. Market investigation and sales promotion are closely related.
B. It is impossible to succeed in selling a product without market investigation.
C. There are various ways of making market investigation.
D. Production goes before market investigation.
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