空气预热器的作用？
参考答案：
空气预热器的作用是利用烟气余热来加热空气可降低排烟温度，提高炉效率，同时用热风进炉又可提高燃烧效率，强化传热效果。
As a film star she was a success, but as a wife she was ________ failure, so their marriage ended in ________ failure.
A．/; /
B．/; a
C．a; a
D．a; /
中药片剂的硬度一般在（）
A.1～2kg
B.2～3kg
C.4～5kg
D.5～6kg
E.8～10kg
