下列哪项属于固定保持器 ()
A.粘固式前牙舌侧保持器
B.标准Hawley保持器
C.改良式Hawley保持器
D.负压压模保持器
E.以上都是
参考答案:A
—John and Lucia got married last week. Did you go to their wedding?
—No, I _________a lecture in another city.
A.gave
B.have given
C.had given
D.was giving
燃料性质和要求的热风温度对锅炉整体布置有何影响?