金瓷冠的金属基底冠由瓷覆盖的部位的厚度一般为（）
A.0.Smm
B.0.6mm
C.0.7mm
D.0.8mm
E.1.0mm
参考答案：A
一You have made great progress in your studies of English，haven’t you?
一Yes，but much _______ ． ‘
A．remains to do
B．is remained to do
C．remains to be done
D．is remained to be done
顶板、侧板、端板、地板腐蚀深度大于板厚的（）时，挖补、截换或更换。
A.40%
B.50%
C.60%
