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【多选题】
食品保鲜膜按材质分为聚乙烯(PE)、聚氯乙烯(PVC)、聚偏二氯乙烯(PVDC)等种类。PVC被广泛地用于食 品、蔬菜外包装，它对人体有潜在危害。下列有关叙述不正确的是 [ ]A.
PVC保鲜膜属于链状聚合物，在高温时易熔化，能溶于酒精
B.
PVC单体可由PE的单体与氯化氢加成制得
C.
鉴别PE和PVC，可把其放人试管中加热，在试管口放置一湿润的蓝色石蕊试纸，如果试纸变红，则是 PVC；不变红，则为PE
D.
等质量的聚乙烯和乙烯燃烧消耗的氧气不一定相等
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举一反三
【单选题】从早上9点开始输液,若使1000ml液体在5小时内滴完,输液速度为
A.
40滴/分 ;
B.
45滴/分 ;
C.
50滴/分 ;
D.
55滴/分 ;
E.
60滴/分
【简答题】What’s the bet between the two brothers?
【多选题】Why should a visitor to a large firm make an appointment in advance?
A.
Because executives are usually quite busy.
B.
Because executives often have to go out on business.
C.
Because executives often do not have much time for visitors.
D.
Because executives are often away from the office.
【简答题】Why should a firm be cautious about entering a licensing agreement?
【单选题】— Li Na went out of the China Open in the first round. Why should she be defeated by such an unknown player? — Well, that's OK. She __________ enough after becoming the world champion. [ ]
A.
could not train
B.
must not have trained
C.
can not train
D.
may not have trained
【单选题】The two brothers are talented in maths, and both of them won the first prize of maths competition. [ ]
A.
similarly
B.
familiarly
C.
frequently
D.
correctly
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