单项选择题
What is the FIRST and most important step in system troubleshooting？（）
A.back up the system data B.gather information about the problem C.try rebooting the system to see if that fixes the problem D.check the System Error Log or Event Log
单项选择题 AdefectiveCD-ROMdriveisreplacedwithanewCD-ROMdrive.ThenewCD-ROMdriveisabletoreadanyCDthatitaccesses，butmusicCDsdonotplaymusic.WhatistheMOSTlikelycauseofthisproblem？（）
