It's six o'clock．It's time to get up．Please ．
A：wake up him
B：wake him up
C：heat up him
D：heat him up
优生就是促使生出的后代在遗传素质上优良些，同时避免生出有遗传疾病的后代．下列哪项措施有利于优生（ ）
为了突出草原上生机勃勃的景象，文章中写草原的天____，空气____，还写了白色的羊群在____，欢乐的牧羊人____ 。
