根据句子意思及首字目提示写出单词的正确形式。
Talking about others' p____  life is not polite.           
I have r____ a special present from my pen pal in Australia.  
Last month, I spent a w____  vacation in the countryside.
I have two pens, but n____  of them works well.
Go down this street and turn left at the second t____ lights.
I'm c____ that he will win first prize in the competition.

Some singers sing songs to r____ money for the poor children.

Rose is so c____  that there is no mistake in her homework.

在实数范围内,下列各式一定不成立的有(    )
(1)$\sqrt{a^2+1}$=0; (2)$\sqrt{a-1}$+a=0; (3)$\sqrt{2a-3}$+$\sqrt{3-2a}$=0;(4)$\frac{1}{a-2}$=0.

自然界只有正、负两种电荷，我们把用绸子摩擦过的玻璃棒带的电荷叫做____ ，同种电荷相互____