对少量的图书文件可采用家用微波炉消毒的方法。将图书文件用（）包裹好，放在微波炉内，在650W功率下，5-10分钟即可。
参考答案：湿布
Unless ____ to speak, you should remain silent at the conference.
A invited B inviting C being invited D having invited
电焊工需持哪些有效证件上岗？
