—What did the teacher say just now?       

—Sorry. I didn't catch it. I _____ about something else.       [ ]

A. think

B. will think  

C. was thinking

D. thinks

车辆采用交叉支撑装置，使转向架的空、重车抗菱刚度较以前提高了（）。

A.1倍

B.3—6倍

C.10倍

D.20倍