中兴公司ZXD5000 100A（V2.0）整流器采用（）电路拓扑结构。
A. 全桥式
B. 相移谐振式
C. 双管正激式
D. 推挽式
抽气充氮是保管较为先进方法，但要求茶叶含水量在（），否则不利储藏。
A. 2-5％
B. 7％
C. 9％
D. 12％
Except as provided for otherwise，an oil tanker might discharge certain amount at certain rate of oil or oily mixtures into sea when（）.
A. the tanker is within 50 nautical miles from the nearest land
B. the tanker is no more than 50 nautical miles from the nearest land
C. the tanker is more than 50 nautical miles from the nearest land
D. the tanker is not more than 50 nautical miles from the nearest land
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