The physics teacher once said that we first _________ the lightning followed by thunders because light _________ faster than sound．

A.see; travelled

B.saw; travelled

C.saw; travels

D.see; travels

答案及解析： C

解析：

第一个空用saw与主语的时态一致；

第二个表示客观真理，仍然要用一般现在时。