皮皮学，免费搜题
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【单选题】
下面哪一个不产生外部性：A.
一个消费者吃一条巧克力
B.
一个企业向空间中排放污染物
C.
一个家庭主妇铲掉家门外面吃力的雪
D.
一个人在一个封闭的环境里吸烟
E.
一个养蜂人的蜜蜂给邻居的果树授粉
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【简答题】短文理解 The most popular form of home entertainment:____1____ __2___ hours per day( 第二段) The next most common leisure activity:_____3____ or _____4_____ ______5______minutes per day (第三段) Spectator sport...
【单选题】β-内酰胺类抗生素的作用机制是
A.
抑制转肽酶，阻止细胞壁的合成
B.
为二氢叶酸合成酶抑制剂
C.
抑制环氧化酶，使前列腺素减少
D.
干扰细菌的生长繁殖而抗菌
E.
β-内酰胺酶抑制剂，阻止细胞的形成
【单选题】Izaak likes to eat pizza and to fish. The more fishing he does the happier he is, up to 8 hours a day. If he fishes longer than 8 hours he gets a sore back and is less happy than if he hadn'tfished at...
A.
20
B.
32
C.
23
D.
18
【单选题】Izaak likes to eat pizza and to fish. The more fishing he does the happier he is, up to 8 hours a day. If he shes longer than 8 hours he gets a sore back and is less happy than if he hadn't shed at al...
A.
$20
B.
$32
C.
$23
D.
$18
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