读一读，选择正确的答案，将字母代号写入前面的括号内。

① Is he nine?      A. Yes, I am.

② Are you a boy?     B. I'm a cow.

③ Are you two?      C. I'm four.

④ How old is your sister？      D. She is ten.

⑤ Who are you?     E. Yes, he is.