下列四个等式中，是一元一次方程的是（　　）

A．x²-1=0

B．x+y=2

C．x=0

D．2+3=7-2

看家谱图，填入恰当的单词将短文补充完整。

I have（有）a good friend. His name is Jim. There are（有）nine people（人）in his family. His 小题1:      have two sons, his小题2:      and his 小题3:     . His parents have two 小题4:      and two 小题5:     . The two girls are Gina and Jane, and the two boys are Jim and Eric. So Jim has（所以吉姆有）two sisters and brother. Jim loves his family. His family love him, too.