Question

they are is a pen in the bag改为否定句和一般疑问句

Answer 1

你这句子明显拼写错误 不对
there is a pen in the bag才对
否定句 is there a pen in the bag
一般疑问句 there is no pen in the bag

Answer 2

They are is a pen in the bag.改为否定句和一般疑问句
They are is a pen in the bag.
否定句：They are is not a pen in the bag.
They are isn't a pen in the bag.
一般疑问句：Are they is a pen in the bag?

Answer 3

There isn't a pen in the bag.
Is there a pen in the bag?