集中供电有哪些缺点？

阅读下列材料：

鸦片战争一声炮响，改变了古老中国的历史命运，在西方列强坚船利炮冲击下，中国步人存亡之秋，仁人志士也一次又一次的奇起，救国救民于苦海。

请回答：

（1）列举近代前期西方列强发动的大规模侵华战争三例，说明中国社会是怎样逐步沦为半殖民地半封建社会的？

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（2）近代前期农民阶级领导的革命斗争有哪两次？两次农民运动失败的相同的主、客观原因各是什么？其失败说明了什么问题？

（3）近代前期，清政府爱国官兵抗击外来侵略的斗争表现在哪些方面？近代列强没有把中国变为其殖民地的主要原因是什么？

茎或枝的作用？

可用于伤寒沙门菌感染的药物为（）。

A．阿莫西林

B．苯唑西林

C．替卡西林

D．非奈西林

E．氨苄西林

Motivation is "the driving force within individuals that impels them to action." And goals are the sought-after results (1) motivated behavior.
Motivation can be either positive or negative (2) direction. We may feel a driving force toward some object or condition, (3) a driving force away from some object or condition. For example, a person may be impelled toward a restaurant to fulfill a need, hunger, and away (4) an airplane to fulfill a need of safety. Some psychologists refer to positive drives (5) needs, wants or desires, (6) negative drives as fears or aversions. (7) , though negative and positive motivational forces seem to differ dramatically (8) terms of physical and sometimes emotional activity, they are basically similar in (9) they both serve to initiate and sustain human behavior. (10) this reason, researchers often refer (11) both kinds of drives or motives as needs, wants and desires.
Goals, (12) , can be either positive or negative. A positive goal is one toward (13) behavior is directed and it is often referred to as an approach object. A negative goal is (14) from which behavior is directed away and it is sometimes referred to as an avoidance object. Since both approach and avoidance goals can be considered objectives of motivated behavior, most researchers refer to (15) types simply as goals. Consider this example. A middle-aged woman may wish to remain (16) attractive as possible. Her positive goal is to appear desirable, and (17) she may use a perfume advertised to make her irresistible. A negative goal may be to prevent her skin (18) aging, and therefore she may buy and use face creams. (19) the former case, she uses perfume to help her achieve her positive goal -- attractiveness; in the (20) case, she uses face creams to help avoid a negative goal -- wrinkled skin.

建筑工程施工安全技术

随着建筑施工技术的发展，脚手架的种类也愈来愈多，按搭设的用途，可分为( )。

A．单排架和满堂架

B．外脚手架和内脚手架

C．扣件式和门式脚手架

D．砌筑架和装修架