—Why doesn't Jack get his TV set repaired?

—I know _____. He wants to buy a new one .[ ]

A.why he doesn't  

B. why doesn't he  

C. how doesn't he  

D. how he doesn't

道床是指支承和固定轨枕，并将其荷载传布于（）的轨道组成部分。

A、大地

B、道路

C、混凝土

D、石碴