函数y=$\sqrt{5-x}+3$ 中，自变量x的取值范围是____ ．

用所给词的适当形式填空

①I have two ____ (brother).

②There are two ____ (family) in the picture.  

③ The old man has no ____ (son) or ____ (daughter).

④ My ____ (father) sister is my aunt.

⑤In the photo his mother's ____ (parent) are on the left.

下列各项不属于生物多样性价值的是（    ）

如图所示，一颗子弹沿水平方向射入悬挂在绳子下端的木块并停留其中，使木块摆动一定的角度，请你分别分次子弹射击木块的过程和木块摆动的过程中，机械能是怎样转移或转化的？

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