相反搏动点
参考答案：
心房、心室搏动时相正好相反，心房收缩时心室舒张，两者的交界点即为相反搏动点。
乙烯精馏塔正常停车时，下列说法正确的是（）。
A．塔顶不凝气返裂解气压缩机
B．洗涤液停送绿油洗涤塔
C．乙烯球罐气相平衡阀开
D．停回流后，塔压由放火炬阀泄压
The number of people present at the meeting _________ about 1000 , a large number of whom _______ experts from abroad.
A．was; was
B．were; were
C．was ; were
D．were; was
