句子排序。
(____)A.Mmm, I want to sleep.
(____)B.It's 7 o'clock.Oh! I am late.
(____)C.Wake up,Jim! It's time to get up.
(____)D.Look!What time is it?
天体系统的层次排列由小到大正确的一项是 ( )
图示为某海区洋流示意图。读图,回答下列问题。
认真观察下面消化系统模式图,据图分析回答下列问题;
专家建议青少年要多吃奶、蛋、鱼、肉等含蛋白质丰富的食品.主要是因为蛋白质是( )