问题补充：
The important sports festival, the Olympic Games, held
every years.
A. is, five
B. are, three
C. is, four
D. are；two
答案：
A. is, five
B. are, three
(答案→)C. is, four
D. are；two
解析：句意：每四年举行一次的奥运会是非常重要的体育节日。根据语境，句子用一般现在时，the Olympic Games作为主语，谓语动词用is，every four years=every other three years每四年，即每隔三年，故选C
