What does NASA plan to do? 查看材料
A.To build one more Hyper-X aircraft.
B.To carry out three more Hyper-X experiments.
C.To make the aircraft fly higher and longer.
D.To test another hypersonic flight at 10 times the speed of sounD.

A.To
B.
B.To
C.
C.To
D.
D.To
E.

【参考答案】

D
推断题。利用题干关键词可以定位到文章的最后一段，可以推断NASA计划下一次研发的超音速飞机的速度将达到声速的10倍。