A:汽车尾气-------光化学污染-------咳嗽和气喘者增多
B:含磷洗衣粉--------水体富营养化--------水栖生物大量死亡
C:人口增多--------空气中CO2浓度增大--------温室效应
D:氟氯烃--------臭氧空洞--------皮肤癌患者增多
双曲线x2-y2=1的左焦点为F,点P为左支下半支上任意一点(异于顶点),则直线PF的斜率的变化范围是 ( )
The job of the speaker
A____
The first thing that you have to do
Write a ____about yourself
The third thing to do
Read the paper to the____
Things you can't do
Don't ____that will make everyone laugh.
The time to get everything ready
____
下列叙述的变异现象,可遗传的是( )