关于地球同步卫星的正确说法是( )
A:同步卫星的经纬度都相同
B:同步卫星的运行周期恒定不变,等于地球自转周期
C:同步卫星距地球的高度都相同
D:同步卫星的运行速度小于地球第一宇宙速度
若U={1,2,3,4,5,6},M={1,2,4},N={2,3,6},则∁U(M∪N)=( )
Swimming club
Do you like to swim? Do you want to swim well? Then we have good teachers to teach you. Opening time:2: 00 p.m ~ 9: 30 p.m
Ticket price: 15 yuan for children, 20 yuan for adults(成人)
Please call Mr. Wang at 877-778
Children dancing club
We are a dancing club for children of 5~14. we have lessons from 9:00 to 10: 30 every Saturday and Sunday.
If you like dancing, just join us.
Call Miss Wu at 263-566
当运动员在起跑线上等待发令枪响的时刻,常常心跳加速、呼吸加快,这是由于____ (填一种激素名称)分泌增多造成的,这是一种____ 调节.
选出适合的答案。
① happy ____ A. 生日
② this ____ B. 快乐
③ birthday____ C. 这个