合同解除是( )而使债权债务关系提前归于消灭的行为。
A.必须经双方的协议
B.必须因为当事人一方的意思
C.因不可抗力
D.因当事人一方的意思或双方的协议
参考答案:D
.从根本上讲,科研课题的产生来自于实践与理论的()。
____________, I still couldn’t figure out what the headmaster said at the conference.
A.Though I didn’t listen attentively
B.Attentively as I listened
C.Attentively as did I listen
D.As long as I listened