下列关于椎间孔的正确叙述是（）。

A.是椎弓和椎体围成的孔

B.是相邻的椎弓围成的孔

C.是相邻椎骨的上、下切迹围成的孔

D.容纳脊髓

It was on my way back home ______ my teacher made the promise______I can do nicely next exam I will buy me a set of LuXun’s Complete Works.

A．when; that

B．when; that if

C．that; why

D．that; that if