对于雷电活动强烈,接地电阻又难以降低的地区中的10-35kV电网,可以考虑采用()或者()的运行方式,作为线路的防雷手段。
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public class MyLogger { private StringBuilder logger = new StringBuuilder(); public void log(String message, String user) { logger.append(message); logger.append(user); } } The programmer must guarantee that a single MyLogger object works properly for a multi-threaded system. How must this code be changed to be thread-safe?()
A. synchronize the log method
B. replace StringBuilder with StringBuffer
C. No change is necessary, the current MyLogger code is already thread-safe.
D. replace StringBuilder with just a String object and use the string concatenation (+=) within the log method
办理结账手续是宾客离店前接受酒店所提供的最后一项服务,许多酒店规定办理结账退房的时间不超过()。
A. 2分钟
B. 3分钟
C. 5分钟
D. 8分钟