—Where is the comic book?

—I brought it to you _______ you were in the reading room yesterday. [ ]

A. when

B. if

C. because

D. before

水表的选择原则正确的是（）。

A.公称通径小于或等于50mm时，应采用旋翼式水表

B.公称通径小于或等于50mm时，应采用螺翼式水表

C.公称通径大于50mm时，采用螺翼式水表

D.在干式和湿式水表中应优先选用湿式水表。