题型:选择题 读某地的地质构造示意图,完成16~18题:小题1:a区域的地质构造名称为( )A.背斜B.向斜C.地垒D.地堑小题2:与东非大裂谷的成因最符合的是( )A.aB.bC.cD.d小题3:①②③④四处的岩层比较,年龄最轻的岩层是( )A.①B.②C.③D.④ 查看答案
题型:单项选择题 On a ship,when may a work vest be substituted for a required life preserver?()A.To replace a damaged life preserverB.For use during fire drillsC.For use during boat drillsD.At no time 查看答案