为什么打哈欠会“传染”

Do you have a problem or some distress you want to chat about?Have som ething to get off your chest?Write to me,your sister“Summer”.有难题或苦恼想跟人聊聊?想将积压心头的忧虑一吐为快?写给我吧,你们的“夏天儿姐姐”。T o:szsxx@ya hoo.com.cn或黑龙江教育杂志社新概念英语阅读版。从来没想过我会被一个小哈欠逼到舌头打结。A:没事儿打什么哈欠,都传染给我了。B:哈欠会传染?!不过是呼出点气体,又不是病毒!A:……The PhysiologicalTheory:W e yaw n to getm ore oxygen(氧气)into oursystem orto rid ourselvesofexcess …