They have been collecting shells for there years.(改为同义句)Has Tom been skating for hours?(做否定回答)My mother has been collecting stamps for about ten years.(向画线句子提问)

问题描述:

They have been collecting shells for there years.(改为同义句)
Has Tom been skating for hours?(做否定回答)
My mother has been collecting stamps for about ten years.(向画线句子提问)