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．氢原子中电子绕核做匀速圆周运动，当电子运动轨道半径增大时,电子的电势能     , 电子的动能增     , 运动周期    .(填增大、减小、不变)

答案

增大 减小  增大 

当电子运动轨道半径增大时,库仑引力做负功，电子的电势能增大，动能减小，运动周期增大

故答案为：增大，减小，增大

问答题

1．预付工程款是多少
2．从第二个月至第四个月每月的工程量价款是多少工程师应签发的工程款是多少实际签发的付款凭证金额是多少
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单项选择题

Lobbying groups often try to disguise a financial self-interest by clumsily dressing up their arguments in the guise of concern for the public. You see this tendency in the pharmaceutical industry (21) in energy and lumber companies who like to tout their (22) of the environment. But (23) , two new books argue, are these tactics more (24) a cause for concern than in agribusiness.
Marion Nestle’s "Food Safety: Bacteria, Biotechnology, and Bio-terrorism’ looks at the way the American meat and biotechnology industries have (25) successfully on Capitol Hill (26) stricter federal regulation, which the author argues has undermined the safety of the food supply.
(27) , Maxime Schwartz’s "How the Cows Turned Mad" (28) the origins of mad-cow disease over more than two centuries, and reveals the fallout from the British government’s blind (29) that the disease could not be (30) to humans.
In 1999, Ms Nestle writes in her earlier book, Rosemary Mueklow, the executive director of the National Meat Association, lobbied against President Clinton’s (31) to establish a more thorough testing regime for E. coli 0157: H7, a potentially (32) pathogen.
Ms Muck low’s organization—which represents meatpackers and processors who (33) to discard or reprocess meat found to be infected under the new testing regime—argued on Capitol Hill that (34) microbial testing in meat could actually lead to a greater public health risk (35) confident consumers might relax their own safe-handling procedures at home.

A. dead B. deadly C. live D. lively
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