It is impolite and inconsiderate for people to drop in uninvited.不请自来是不礼貌和不体谅别人的。She used to drop in for a chat quite often.她以前常常会进来聊聊天。CBS will end the series if it continues to drop in the ratings.这部电视连续剧如果收视率排名继续下降，哥伦比亚广播公司就会停播该剧。I'd like to drop in and see you sometime next week.我想在下周什么时候顺便来看看你。