Our teacher said sound much more slowly than light.
A. was traveling
B. travels
C. has traveled
D. traveled
网友回答
A. was traveling
(答案→)B. travels
C. has traveled
D. traveled
解析：此题考查宾语从句的时态问题。当主句的谓语动词是一般现在时时，其宾语从句的时态可以是任何适当的时态。所以，宾语从句的时态应根据实际情况而定。当主句的谓语动词的时态是一般过去时的时候，其宾语从句的时态一般要用任一适当的过去时态。但是当宾语从句是表达客观真理和规律的句子时，其时态仍旧用一般现在时。