一、选择题 1.如果命题“p且q”是假命题,“非p”是真命题,那么( ) A.命题p一定是真命题 B.命题q一定是真命题 C.命题q可以是真命题也可以是假命题 D.命题q一定是假命题 2。若m是2和8的等比中项,则圆锥曲线的离心率是( ) A。 B。 C。或 D。
1.下列叙述正确的是 A.pH=4的硫酸溶液中c(H+):c(SO42-)等于2:1,稀释10000倍后二者的比值几乎不变 B.由水电离的c(H+)=10-12mol/L的溶液中K+、Ba2+、Cl-、Br-、HCO3-一定能大量共存 C.1.0×10-3mol/L盐酸溶液的pH=3,则1.0×10-8mol/L盐酸溶液的pH=8 D.某温度下水的离子积为1.0×10-12,等体积pH=1的H2SO4溶液与pH=11的NaOH溶液混合后溶液呈中性
Welcome to Arundel Castle which is situated in West Sussex, England. The castle has a history of nearly 1000 years and has welcomed visitors traveling from all over the world. Arundel Castle also plays a starring role in many films.
一、单选题(每道题4分,共32分) 1.如图,用起电机使金属鸟笼带电,站在内置金属架上的鸟安然无恙,且不带电,其原因是 ( ) A.鸟的脚爪与金属架绝缘 B.鸟与笼电势不同,有电势差 C.起电机使笼带电,笼的电势不会很高 D.鸟笼内部场强为零,电荷分布在笼的外表面
一、选择题(每题3分,共36分) 1。若与的等差中项为,则( ) A. B. C. D.不确定 2。设{an}是首项为a1,公差为-2的等差数列,Sn为其前n项和,若S1,S2,S4成等比数列,则a1=( ) A.8 B.-8 C.1 D.-1 3.在△ABC中,若,则此三角形中最大内角是( ) A.60° B.90° C.120° D.150° 4.设等差数列的前项和为,若,,则当取得最小值时( ) A.6 B.7 C.8 D.9
一、选择题(每题3分,共36分) 1。若与的等差中项为,则( ) A. B. C. D.不确定 2。设{an}是首项为a1,公差为-2的等差数列,Sn为其前n项和,若S1,S2,S4成等比数列,则a1=( ) A.8 B.-8 C.1 D.-1 3.在△ABC中,若,则此三角形中最大内角是( ) A.60° B.90° C.120° D.150°
1. What’s wrong with the man’s watch? A. It goes slowly. B. It goes too fast. C. It doesn’t work sometimes. 2. When will the speakers meet? A. At 2:00. B. At 4:00. C. At 6:00.
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