给试管里的物质加热,下列操作正确的是( )
A.用酒精灯灯焰的外焰部分
B.直接将灯焰固定在放固体的部位
C.用手拿着试管
D.液体体积超过试管容积的23
答案:A
关于淤积性皮炎描述错误的是()。
A.好发于四肢
B.可伴有不同程度静脉曲张
C.可形成溃疡,并遗留色素沉着
D.处理可采用抬高患肢并用弹力绷带等方法
E.反复发作者可采用曲张静脉根治术
(66) is defined as the buying and selling of products and services over the Internet. It had included the handling of purchase (67) and funds transfers over computer networks from its inception.
A.Electronicmail
B.Searchengine
C.Multimedia
D.Electroniccommerce