原料乙苯产品中必须控制二乙苯含量的目的是()。
A、防止二乙苯的浪费损失
B、降低装置的能耗
C、防止重组分带入塔顶
D、防止苯乙烯单元中形成难溶的聚合物
参考答案:D
— I stayed at a hotel while in New York.
—Oh, did you? You ___ with Barbara.[ ]
A. could have stayed
B. could stay
C. would stay
D. must have stayed
痢疾的病位在
A.脾B.胃C.中焦D.肠E.肝胆