省煤器属于（）式换热器。
A.混合
B.表面
C.回转
D.回热
参考答案：B
25. The book ______forty maps, ______three of Great Britain.
A．contains; includes
B．is containing; including
C．includes; contains
D．contains; including
引起尿液混浊的原因有哪些？
