Which statement at Point X on line 1 allows this code to compile and run？（） [" import java.io.*.；"," include java.io.*；"," import java.io.PrintWriter；"," include java.io.PrintWRiter；"," No statement in needed."]
多次弯曲造成的（）是钢丝绳破坏的主要原因之一。 ["弯曲疲劳","扭转","拉伸","变形"]
“金三角”位于老挝、泰国、缅甸与我国接壤，盛产罂粟，是（）的主要毒源地。 ["海洛因","咖啡因","冰毒","可卡因"]
整群抽样
达鲁花赤
系统抽样
