①函数f（x）=x+ 9x 的最小值为6；
②不等式 2xx+1 ＜1的解集是{x|﹣1＜x＜1}；
③若a＞b＞﹣1，则 a1+a ＞ b1+b ；
④若a＞b，c＞d，则ac＞bd．
所有正确命题的序号是____．
①____ What's your friend's name? A．Yes, she is.
②____ Does she have long hair? B．Yes, they are.
③____ Are they good friends? C．He's short.
④____ Is your brother tall or short? D．Yes, she does.
⑤____ Is she thin? E．Liu Tong.
一年中，人们如果想在最早时间参加北京天安门广场的升旗仪式，应选择
