封发关系分为（）三种。
A、互封、直封、临封
B、集封、直封、临封
C、单封、混封、集封
D、单封、混封、临封
参考答案：A
Cooperation or teamwork, the importance of which is often _____, plays an important part in
football matches. [ ]
A. stressed
B. counted
C. paid attention to
D. talked
老师买了3个篮球和50个乒乓球共用294元，1个篮球的价钱相当于16个乒乓球的价钱。每个篮球多少元？
