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【简答题】
重500N的长方体大木箱放在水平地面上，木箱与地面的接触面积是0.4m 2 ，求： （1）木箱对地面的压强是多少？ （2）一个重600N的人用小车将这个大木箱从斜面底部推上斜面顶部，如图10所示．已知斜面的长是4m，斜面的0.5m，人沿斜面方向的推力F大小是80N，问有用功是多少？斜面的机械效率约是多少（保留两位有效数字）？
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【单选题】热继电器和熔断器的作用分别为 。
A.
热继电器：短路保护；熔断器：断路保护
B.
热继电器：过载保护；熔断器：断路保护
C.
热继电器：过载保护；熔断器：短路保护
D.
热继电器：短路保护；熔断器：过热保护
【多选题】为避免大体积混凝土由于温度应力作用而产生裂缝，可采取的措施有( )。
A.
适当降低水灰比，减少水泥用量
B.
适当提高水灰比，增加水泥用量
C.
降低混凝土的入模温度，控制混凝土内外的温差
D.
留施工缝
E.
优先选用低水化热的矿渣水泥拌制混凝土
【多选题】为大体积混泥土由于温度应力作用产生裂缝,可采取的措施有( )。
A.
提高水灰比
B.
减少水泥用量
C.
降低混泥土的入模温度,控制混泥土内外的温差
D.
留施工缝
E.
优先选用低水化热的矿渣水泥拌制混凝土
【简答题】肿瘤临床治疗的三大主要手段为( )、( )和( )。
【单选题】Why does Becky Lodewyck say online classes have the potential to hold students more accountable?
A.
Because many st~dents have worked before they return to education.
B.
Because students must complete at least 100 hours of field experience.
C.
Because everyone has to be fully engaged in the work.
D.
Because students have a strong sense of responsibility.
【简答题】A. Female students are unfit for studying physics. B. He can serve as the woman's tutor. C. Physics is an important course at school. D. The professor's suggestion is constructive.
【单选题】Male and female students are quite different from each other ______ the age at which they begin
A.
81. Male and female students are quite different from each other ______ the age at which they begin to develop an intellectual self-discipline. A．with regard to
B.
in the light of
C.
in honor of
D.
on account of
【简答题】肿瘤临床治疗的三大主要手段?
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