B)根据句子意思，用括号中所给的单词适当形式填空。
____  ▲  (wolf) belong to the dog family, living and hunting together.
____ With the money donated, we have   ▲ (success) helped many poor young girls return to school.
____ If we always keep our worries to   ▲  (we), things will get even worse.
____ Our head teacher warned us   ▲ (not fly) kites near power lines in spring.
____ Though it seemed   ▲  (hope) to pass the exam, he still kept on trying.
____ A recent scientific report says three   ▲  (eight) of the school students suffer from sub-health(亚健康).

形 $\sqrt{m\pm 2\sqrt{n}}$ 的化简，只要我们找到两个数a，b（a＞b），使a+b=m，ab=n，则

$\sqrt{m\pm 2\sqrt{n}}=\sqrt{a+b\pm 2\sqrt{ab}}$ = $\sqrt{{(\sqrt{a})}^2\pm 2\sqrt{ab}+{(\sqrt{b})}^2}$ = $\sqrt{{(\sqrt{a}\pm \sqrt{b})}^2}$ = $\sqrt{a}$ ± $\sqrt{b}$

例：化简

$\sqrt{7+4\sqrt{3}}$ = $\sqrt{7+2\sqrt{12}}$ = $\sqrt{4+2\sqrt{4\times 3}+3}$ = $\sqrt{{(\sqrt{4})}^2+2\sqrt{4\times 3}+{(\sqrt{3})}^2}$ = $\sqrt{{(\sqrt{4}+\sqrt{3})}^2}$ =2+ $\sqrt{3}$

解：用上述例题方法的化简：