其他（共1小题）
I haven’t decided when we should start ．（同义句转换）
I haven’t decided_________________ start ．
Why did he go to bed so early ? I don’t know ．（合并句子）
I don’t know_______ he_______ to bed so early．
He put down the things before leaving ．（变为否定句）
He                       down the things before leaving。
He usually learns English by taking notes ．（对划线部分提问）
_______does he usually_______ English ?