赠与合同属于()。
A.双务合同
B.单务合同
C.主合同
D.从合同
参考答案:B
Not until the party had begun _____. [ ]
A. he did arrive
B. didn't he arrive
C. he arrived
D. did he arrive
人体之所以成为一个统一的整体,是由于________调节和________调节等的作用。