根据危险货物的危险程度不同,将其分为()。
A.三级
B.二级
C.四级
D.五级
参考答案:B
诊断鼻窦霉菌的最佳检查方法是:()
A.平片
B.CT平扫
C.CT增强扫描
D.MRI
E.B超
A trade barriers is a general term that describes any government policy or regulation that restricts international trade.( )