中枢痉挛多见于（）
A.健康青壮年
B.老年人
C.未能适应高温者
D.儿童
E.重危患者
参考答案：A
A distress signal（）.
A.consists of 5 or more short blasts of the fog signal apparatus
B.consists of the raising and lowering of a large white flag
C.may be used individually or in conjunction with other distress signals
D.is used to indicate doubt about another vessel's intentions
有机防水涂料抽检时，按每（）为一批。
A.1吨
B.2吨
C.3吨
D.5吨
