“MN是经过椭圆 （a＞b＞0）的焦点的任一弦，若过椭圆中心O的半弦 ，则 .”类比椭圆的性质，可得“MN是经过双曲线 （a＞0，b＞0）的焦点的任一弦(交于同支)，若过双曲线中心O的半弦 ，则____.”

洋葱(见右图)被誉为“蔬菜皇后”。切洋葱时可闻到刺激性气味，这说明  （   ）

“生活中处处有物理”，下列生活中的用电器或现象与物理知识对应正确的是（　　）

____ Since he fell off the bike, John _____________（stay） in bed for a week．
____ ——What is his plan after leaving school?——He _______________（go） to Beijing for education．
____ Could you please ________________（not speak） so loud?
____ David preferred __________（sell） newspapers to doing housework when he was young．
____ The teacher has finished ________________（interview） the parents．
____ You _________________（not laugh） at disabled people．It's impolite．
____ If I ________（be） you, I would help the homeless people．
____ You should say “Thank you” when you ________（give） something as a present by your friends．
____—— I called you yesterday night, but you were not at home．——I ____________（drive） home on the way at that time．
____ Young children should __________（allow） to choose their own clothes．