如图所示，一个挂在绝缘细线下端的带正电的小球B，静止在图示位置，若固定的带正电的小球A的电荷量为Q，B球的质量为m，带电荷量为q，θ=30°，A和B在同一条水平线上，整个装置处于真空中．求：

如图，△ABC内接于⊙O，若∠OAB=30°，则∠C的大小为 （ ）

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.