在研究的设计阶段经常采用控制混杂因素的方法是（）
A.校准仪器
B.限制
C.采用分层分析方法
D.设计多种对照
E.培训调查员
参考答案：B
为贬低他人而取绰号的行为侵犯了公民的[ ]
A．隐私权
B．名誉权
C．肖像权
D．健康权
— Where are the children? The dinner is going to be completely ruined.
— I wish they _____ always late. [ ]
A. weren't
B. hadn't been
C. wouldn't be
D. wouldn't have been
