Question

【题目】The zoo keeper is worried because the number of visitors _______ smaller and smaller.
A.become
B.are becoming
C.is becoming
D.have became

Answer 1

【答案】C
【解析】句意：动物管理员变得很焦急，因为游客人数正变得越来越少。the number of+名词作主语，后面的谓语动词要用单数，A，B三项的主语都得是复数；数字的变化和管理员的焦急是同时进行的，所以要用现在进行时．故选C。