无论m为何实数，直线y=2x+m与直线y=﹣x+3的交点都不可能在（　　）

①除去乙烷中少量的乙烯：光照条件下通入Cl₂，气液分离

②除去乙酸乙酯中少量的乙酸：用饱和碳酸钠溶液洗涤，分液、蒸馏

③除去C₂H₆中少量的C₂H₄：气体通过盛有酸性高锰酸钾溶液的洗气瓶

④除去乙醇中少量的乙酸：加足量生石灰，蒸馏．

点拨："leave sth.＋介词短语"意为"把……留在……"。如：

今天早上我急着去上学，所以把书包落在家里了。 ____

    Job interviews can be very different from country. An interviewer's “body language” and questions, and the form of an interview are not the same around the world.

    If you're at a job interview in Japan, don't look directly into the eyes of the interviewer. It is considered impolite. But if you're at an interview in the US, you should make eye contact(交流) with the interviewer. If you don't, the interviewer may think you are not sure about your ability.

    In the US and some other countries, interviewers aren't supposed to ask questions about family and personal information. In most countries, however, personal questions are very common during job interviews.

    In Germany, your interview might begin with a very short conversation followed by a formal(正式的) interview. In Mexico and many other countries, the whole interview might not be formal.