单选题
We see lighting (before we hear) the thunder (because) sound travels (more slowly) than (light is).
A. before we hear B. because
C. more slowly D. light is
A
B
C
D
【正确答案】
D
【答案解析】
改为sounddoes．比较项是动词travel，故重复的话应用助动词does．
提交答案
关闭