根据句意及句首字母提示完成句子
问题描述：
根据句意及句首字母提示完成句子
A hundred years is a c----------- .
You must k-------- at the door before coming in .
The temperature will fall b-------- zero .
Jack is coming up to the blackboard.He`s walking t-------- the teacher`s desk .
We d-------- them into two groups according to their ages .
答
1 century 世纪
2 knock 敲（门）
3 below 在……下
4 towards朝,向
5 divided 分