英语肯定句变否定句和一般疑问句。

1. 肯定句: She teaches us Chinese.

   否定句: She doesn't teach us Chinese.

   一般疑问句: Does she teach you Chinese?

2. 肯定句: My brother is playing the piano.

   否定句: My brother isn't playing the piano.

   一般疑问句: Is your brother playing the piano?

1.否：She doesn't teach us Chinese.
疑：Who teaches our Chinese?
2.否：My brother isn't playing the piano.
疑：Is my brother playing the piano.

She doesn't teach us Chinese .
Dose she teach you Chinese ?
My brother is not playing the piano.
Does your brother play the piano ?

She doesn't teach us Chinese.
Dose she teach us Chinese?

My brother is not playing the piano.
Is my brother playing the piano?