次要成膜物质在涂料中的作用有（）。
A.可以单独成膜
B.增加涂料的品种
C.改善涂膜性能
D.决定涂膜性质的主要因素
参考答案：B, C
.I hope I will not be called on in class as I’m not yet____prepared．
A．attentively
B．readily
C．actively
D．adequately
What's the best present you have ever ________? [ ]
A. received
B. receives
C. receiving
