Tom often plays basketball_____ his friends. [ ]
A. to
B. with
C. on
D. at
答案:B
这一章节在上下文中起什么作用?
合同可变更、撤销的前提是( )。
A.损害国家利益
B.违反法规
C.当事人提出请求
D.当事人一方违约