环境空气质量监测中，用碱片—铬酸钡分光光度法测定硫酸盐化速率时，需向样品溶液中加铬酸钡悬浊液，铬酸钡悬浊液在加入前要充分振摇均匀。
参考答案：对
Soon comics were so prevalent as to attract the attention of serious critics.
A．successful
B．prosperous
C．widespread
D．persuasive
非上市证券不能在证券交易所内交易，也不能在其他证券交易市场交易。( )
