In order to keep the balance of ecosystem, every possible means _______to deal with the problems of the over-exploiting of natural resources.
A.has tried | B.has been tried | C.have taken | D.have been taken |
相关知识点
推荐套卷
In order to keep the balance of ecosystem, every possible means _______to deal with the problems of the over-exploiting of natural resources.
A.has tried | B.has been tried | C.have taken | D.have been taken |