接近地球表面的一层是()
A、对流层
B、中间层
C、平流层
D、电离层
参考答案:A
It is ____ he often fails in exams ____ makes his parents worried about him. [ ]
A. what; that
B. that; what
C. that; that
D. /; that
在下列内容中,属于设计阶段质量控制任务的是()
A.配合设计单位优化设计
B.限额设计
C.审查阶段性设计成果
D.对设计方案进行技术经济分析