数词+hundred/thousand/million/billion+名词复数

　　hundreds/thousands/millions/billions of+名词复数

　　例

　　1. __people go swimming in summer in Dalian.

　　A、Thousands B、Thousand of C、Thousands of D、Thousand

　　2. __the students will take part in this English speech contest.

　　A. Two hundred of B. Two hundreds of C. Hundreds of D. Hundred of