过热器汽温与再热器汽温变工况时，两者之间温差应控制在什么范围之内？
参考答案：
15℃。
以下所述牙体缺损的原因哪项是错误的（）
A.酸蚀症
B.楔状缺损
C.发育畸形
D.戴垫
E.夜磨牙
On his way to school, he was _____.
A．robbed of his money
B．stolen from his money
C．robbed from his money
D．stolen of his money
垫