看工艺流程图时，要先看（）。
A.主要管线、次要设备
B.次要管线、次要设备
C.次要管线、主要设备
D.主要管线、主要设备
参考答案：D
—Lucy has gone to China for her holiday.
—Really?When________back?[ ]
A. is she coming
B. did she come
C. had she come
D. has she come
一个直棱柱有12个顶点，所有侧棱长的和为72cm，则每条侧棱长为______cm．
