问题描述:
which 后面为什么还用has been 这个时态,我认为应该用过去完成时
A new machine called 'The Revealer' has been invented and it has been used to detect gold which has been buried in the ground.
A new machine called 'The Revealer' has been invented and it has been used to detect gold which has been buried in the ground.
问题解答:
我来补答展开全文阅读