Please help yourself to the seafood.（）
A. Thanks, but I don't like the seafood
B. Sorry, I can't help
C. Well, fish don't suit for
D. No, I can't
When the power of SART is on, it will（）.
A. transmit distress signal
B. send response signal
C. transmit the signal of ship‟s position
D. be start by X-band radar
首选于白喉、百日咳带菌者、支原体肺炎、衣原体感染及军团菌病的药物是（）
A. 青霉素G
B. 氯霉素
C. 红霉素
D. 四环素
E. 土霉素
《联合国国际货物买卖合同公约》规定在哪些情况下发价一旦生效即不能撤销？
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