I suppose they must be trying out new ideas in the lab的反义疑问句为什么是need not they?

I suppose they must be trying out new ideas in the lab的反义疑问句为什么是need not they?
I suppose they must be trying out new ideas in the lab的反义疑问句为什么是need not they?

I suppose they must be trying out new ideas in the lab的反义疑问句为什么是need not they?
首先I suppose等句子反义的是后面的从句,must反义用need,具体原因不清楚记着就行啦

是must 的反义疑问