题目内容

金属屏护装置必须采用保护接地或接零，以防止屏护装置意外带电而造成触电事故。

A. 正确
B. 错误

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怎样理解人的自觉活动与社会历史客观必然性的关系？

锚栓抗拔承载力现场检验可分为非破坏性检验和破坏性检验。（）

A. 正确
B. 错误

A web application uses the HttpSession mechanism to determine if a user is "logged in." When a usersupplies a valid user name and password， an HttpSession is created for that user. The user has access tothe application for only 15 minutes after logging in. The code must determine how long the user has beenlogged in， and if this time is greater than 15 minutes， must destroy the HttpSession. Which method in HttpSession is used to accomplish this？（）

A. Getcreationtime
B. Invalidateafter
C. Getlastaccessedtime
D. Getmaxinactiveinterval