服务
参考答案：是指伴随着供方与顾客之间的接触而产生的无形产品。
规定：x○y= 3x - 2y。已知：x○（4○1）= 7，求x的值。
We had great fun ________the volleyball match between the Chinese team and Japanese team.
A．watch
B．watched
C．watches
D．watching
