词根学习第250天: plac, pleas=安慰, 高兴, 满意 秒懂单词| 自满的complacent, 安慰剂placebo, pleased, pleasing, pleasant-词根UP单词量 1.串placid, please, unpleasant, pleasure, displease 2.“不用谢”不只是you're welcome, 补充7种表达