问题补充：
Our physics teacher told us that light faster than sound.
A. travel
B. travels
C. is travelling
D. has travelled
答案：
A. travel
(答案→)B. travels
C. is travelling
D. has travelled
解析：本题考查的是宾语从句，一是考虑到语序应该为陈述句语序，二是考查的是从句的时态要与主句的时态一致，但是客观现实，要用一般现在时，故选B
