— We'll make a trip to Hainan Island next weekend. Will you go with us?

— No, I can't _____ it at present. [ ]

A. afford

B. save

C. offer

D. accept

一立体的一面投影是三角形，另两面投影是矩形，这个立体是（）

A.三棱柱

B.三棱锥

C.圆柱

D.三棱台