问题补充:
A number of birdwatchers in Zhalong Nature Reserve. The number of them500.
A. are, are
B. is, is
C. is, are
D. are, is
答案:
A. are, are
B. is, is
C. is, are
(答案→)D. are, is
解析:句意:许多观鸟者在扎龙自然保护区。他们的数量是500。A number of 许多,修饰复数名词,含有A number of 的短语作主语,谓语动词使用复数形式;The number of···的数量,用作主语时,谓语动词使用第三人称单数形式。所以选D。