PFM的金属热膨胀系数远远大于瓷的热膨胀系数时易产生
A．嵌体B．半冠C．烤瓷熔附金属全冠D．桩冠E．3/4冠
参考答案：D
在同一平面内，两条直线的位置关系只有（ ）和（ ）。当（ ）相等或（ ）相等或（ ）互补时，两直线平行。
Don't blame him for breaking that vase. ____ he is a child. [ ]
A. Even though
B. In fact
C. After all
D. At first
