箱式电梯是一种以电动机驱动的垂直升降机，用于多层建筑乘人或载运货物．当电梯加速上升时，以____ 为参照物，乘客是静止的；电梯从一楼开始上升时，里面有很多乘客，在到达顶层的过程中，有乘客在不同楼层陆续离开电梯、但始终没有再上新的乘客，这一过程中，电梯的效率将____ （选填“逐渐提高”、“逐渐降低”或“保持不变”）．

根据短文内容，完成下列小题。

        New rules and behavior standards (行为规范) for middle school students came out (颁布) in March. Middle schools are going to use a new way to decide who the top students are. The best students won't only have high marks. The following are some of the new rules.

        Tell the truth. Have you ever cheated(作弊) in an exam? Don't do it again! That's not something honest students should do.

        Love animals and other people. Good students love animals and care for other people. April is Bird loving Month in Beijing this year. Is your school doing anything to celebrate it? You should join! In that way, you can learn more about animals and how to protect(保护) them.

        Be open to new ideas. Have you ever thought people could live on the moon? Maybe you'll find another earth in space in the future. Everyone's new ideas are important.

        Protect yourself. Has a thief ever taken money from one of your classmates? Don't let it happen to you. If you have to go back home late, you should let your parents know.

        Use the Internet carefully. The Internet can be very useful for your study. But some things on the Internet aren't for kids, so try to look at the good web pages (网页). You can use the web pages for fun or homework.

    崔寔字子真，一名台，字元始。少沉静，好典籍。父卒，隐居墓侧。服竟，三公并辟，皆不就。桓帝初，诏公卿郡国举至孝独行之士。寔以郡举，征诣公车，病不对策，除为郎。明于政体，吏才有馀，论当世便事数十条，名曰《政论》。指切时要，言辩而确，当世称之。仲长统曰：“凡为人主，宜写一通，置之坐侧。”其后辟太尉袁汤大将军梁冀府并不应大司农羊傅少府何豹上书荐寔才美能高宜在朝廷。召拜议郎，迁大将军冀司马，与边韶、延笃等著作东观。出为五原太守。五原土宜麻，而俗不知织绩，民冬月无衣，积细草而卧其中，见吏则衣草而出。寔至官，斥卖储峙，为作纺绩、织纴之具以教之，民得以免寒苦。是时胡虏连入云中、朔方，杀略吏民，一岁九奔命。寔整厉士马，严烽候，虏不敢犯，常为边最。以病征，拜议郎，复与诸儒博士共杂定《五经》。会梁冀诛，寔以故吏免官，禁锢数年。时，鲜卑数犯边，诏三公举威武谋略之士，司空黄琼荐寔，拜辽东太守。行道，母刘氏病卒，上疏求归葬行丧。母有母仪淑德，博览书传。初，寔在五原，常训以临民之政，寔之善绩，母有其助焉。服竟，召拜尚书。寔以世方阻乱，称疾不视事，数月免归。初，寔父卒，剽卖田宅，起冢茔，立碑颂。葬讫，资产竭尽，因穷困，以酤酿贩鬻为业。时人多以此讥之，寔终不改。亦取足而已，不致盈余。及仕官，历位边郡，而愈贫薄。建宁中病卒。家徒四壁立，无以殡敛，光禄勋杨赐、太仆袁逢、少府段颊为备棺椁葬具，大鸿胪袁隗树碑颂德。

（节选自《后汉书·崔寔传》）