I can see the cat. It's _____ floor. [ ]
A. on a
B. in the
C. at the
D. on the
答案:D
有地图指向标的地图,其指向标的箭头指示的方向一般为
A.北向
B.南向
C.西向
D.东向
一次风机必需是离心式风机。()