我国东部濒临的海洋，从北到南依次是：(    )
①黄海          ② 东海          ③渤海          ④南海

已知映射$f:A\to B$,其中A=B=R，对应法则$f:x\to y=x^2-2x+2$若对实数$k\in B$，在集合A中不存在原象，则k的取值范围是          (  ）

某校根据新课程标准改革的要求，开设数学选修系列4的10门课程供学生选修，其中4﹣1，4﹣2，4﹣4三门由于上课时间相同，所以至多选一门，根据学分制要求，每位同学必须选修三门，则每位同学不同的选修方案种数是（  ）

Some advice(忠告)：

    ⑴ Always play in a safe place. A park is a safe place because there are no cars or trucks. But do not talk to anyone you do not know. Never go with a stranger into a motor car.

    ⑵ Before crossing the road， stop and look both ways. Look left， look right， look left again.

    ⑶ Keep away from houses or building that are being built or knocked down. Something might fall on your head， or you might cut yourself on broken grass.

    ⑷ Medicines or pills can be dangerous. Never swallow（吞下）any pills or medicines you find in the cupboard.

    ⑸ Wear a life jacket whenever you go out in a boat. Even if you are not in the open sea and the water is not deep， you should have your life jacket on. It's easy to fall out of a boat.

    ⑹ Do not put your head out of a car， bus or train. Many children have been killed by doing this.