下列各式3x﹣2，2m+n=1，a+b=b+a（a，b为已知数），y=0，x²﹣3x+2=0中，方程有（　　）

    It was Sunday today. Tom with her two good friends are going to see his uncle . There are lots of apples trees on his uncle farm. But he is too busy to pick the apples in them. So Jim went to help him every year. The farm is no far from here. The children are all going there on bike . They think it's good for their healthy.

下列不属于青春期发育特征的是（　　）

威廉·萨默塞特·毛姆(1874—1965)，20世纪____著名的____、剧作家和散文家。1874年生于巴黎英国大使馆，其父罗伯特·奥蒙德·毛姆担任使馆的法律顾问。毛姆天性害羞，体质孱弱又孤僻口吃，这使他养成了反思的习惯，成为一个生活的冷眼旁观者。毛姆在19世纪末开始写作，但是他的主要创作活动时期是在____开头的四十多年。

关于下列四个实验的认识中，正确的是（　　）