如图所示,在x轴上方存在着垂直于纸面向里、磁感应强度为B的匀强磁场,一个不计重力

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问题:

如图所示,在x轴上方存在着垂直于纸面向里、磁感应强度为B的匀强磁场,一个不计重力的带电粒子从坐标原点O处以速度v进入磁场,粒子进人磁场时的速度方向垂直于磁场且与x轴正方向成120°角,若粒子穿过y轴正半轴后在磁场中到x轴的最大距离为a,则该粒子的比荷和所带电荷的正负是(  )

A.,正电荷

B.,正电荷

C.,负电荷

D.,负电荷

考点:带电粒子在匀强磁场中的运动
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孙先生,38岁,对称性全身小关节肿痛反复发作5年,有晨僵,热水浸泡后减轻。化验:类风湿因子阳性。拟诊为类风湿关节炎。

随后发现双手指在掌指关节处向尺侧偏斜,应考虑()。

A.因疼痛而挛缩

B.一侧肌张力偏高

C.长期晨僵所致

D.掌指关节半脱位

E.尺侧血供不足

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下列关于元素周期律和元素周期表的叙述中正确的是 [ ]

A.同一主族的元素,从上到下单质熔点逐渐升高

B.元素周期表是元素周期律的具体表现形式

C.同一周期从左到右,元素原子半径逐渐增大

D.周期表中第ⅣA-ⅦA主族元素可表现正化合价

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硝化细菌是分解者。()

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A federal judge on Monday certified a $200 billion class action lawsuit against the tobacco industry for its marketing of light cigarettes.
Eastern District of New York Judge Jack B. Weinstein’s 540-page opinion in Schwab v. Philip Morris USA, Inc., 04-CIV-1945—which included an additional 965 pages of appendices for a total of 1,505 pages—gave tens of millions of smokers an avenue to recover damages from the nation’s largest tobacco companies, including Philip Morris USA Inc., R.J. Reynolds Tobacco Co., Lorillard Tobacco Co., and Liggett Group, Inc.
The class will include anyone who purchased light cigarettes from the time tobacco companies began selling them in the 1970s. The judge said he even would consider broadening the class, to encompass smokers of all "low tar" brands, not just light cigarettes. The judge suggested that an expansion of the class could assist the parties in negotiating a global settlement. He set a trial date for January 22, 2007. The plaintiffs intend to seek treble damages.
einstein has expressed skepticism about the plaintiffs’ theory of damages, which alleges that light smokers were defrauded of billions because they believed they were buying a product of greater value because of its health advantages. The judge also questioned the size of the class, as well as the claim that as many as 90 percent of light cigarette smokers chose the cigarettes because they were less harmful.
In his ruling Monday, the judge stressed that while the suit was far from perfect, the evidence was sufficient. He said the jury system—which he described as the "ultimate focus group of the law"—was well equipped to sort out the particulars in accordance with Amendment Ⅶ of the U.S. Constitution.
Weinstein declined to grant an interlocutory appeal to the 2nd U.S. Circuit Court of Appeals. Theodore M. Grossman of Jones Day in Cleveland, which represents R.J. Reynolds, said the defendants would seek a stay and appeal the class certification under Rule 23(f)of the Federal Rules of Civil Procedure.

Obviously, the passage states that the lawsuit being briefed is between ______ .

A.Schwab and Philip Morris USA, Inc.

B.Jack B. Weinstein and Philip Morris USA, Inc.

C.tens of millions of smokers and Philip Morris USA, Inc.

D.any light cigarette smokers and Philip Morris USA, Inc.

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在国境口岸发现检疫传染病、疑似检疫传染病,或者有人非因意外伤害而死亡并死因不明的,国境口岸有关单位和交通工具的负责人,应当立即向()报告,并申请临时检疫。

A.最近的卫生检疫机关

B.指定的卫生检疫机关

C.目的地卫生检疫机关

D.国境卫生检疫机关

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