重点讲解:
1. birth rate 出生率
America's birth rate fell to a record low last year.
美国去年的出生率降到了创纪录的最低点
。2. depend on 取决于;依赖
He was the sort of person you could depend on.
他这个人你是可以信赖的
。3. hold off 拖延
Could you hold off making your decision for a few days?
你能推迟几天再作决定吗
4. hold back 隐瞒;退缩;抑制
The police had to use force to hold back the crowd.
警察不得不用武力阻止人群
。