冒口有什么作用?如何设置冒口?
参考答案:
补缩,排气,集渣,观察浇注情况(明冒口是是否浇满的标志)。冒口一般设置在型腔的最高部位或壁厚最大处,需补缩的部位。
Jenny did good job in the exam and as reward her parents took her to Beijing last September .
A.a ; the
B.a ; a
C./ ; a
D./ ; the
取药材数粒,加水共研,产生苯甲醛特殊气味的是().