轴测图是将物体连同其坐标轴，用（）法投射到单一投影面上所得到的具有三维图形。
A.中心投影
B.平行投影
C.正投影
D.斜投影
参考答案：B
Peter was so excited he received an invitation from his friend to visit Chongqing. [ ]
A. where
B. that
C. when
D. why
尖晶石是均质体？还是非均质体？
