They try to find out the reason for the problem_______they could salve itA.even though B.even since C.so that D.only when请详细解释一下、、、、、、、、、

问题描述:

They try to find out the reason for the problem_______they could salve it
A.even though B.even since C.so that D.only when
请详细解释一下、、、、、、、、、