复合树脂充填体为加宽釉质酸蚀刻带的宽度,洞缘釉质壁应制成()。
A.30°角短斜面
B.45°角短斜面
C.60°角短斜面
D.135°角内倾斜面
E.120°角内倾斜面
参考答案:B
.If I _____ the money, I would have bought a much bigger car.
A.possessed
B.owned
C.had
D.had had
力是物体间的相互作用,使物体产生变形的效应称为力的()效应。