中国石油大学 / 中石油
正确率:100%
23. if, when _____ up their contract, buyer and seller have some commonly understood rules to specifically refer to, they can be sure of defining their respective responsibilities simply and safely.
A、drawing
B、draw
C、to draw
D、drawed
A、drawing
B、draw
C、to draw
D、drawed
参考答案: