彩色多普勒的取样框调节过大,会出现的现象是()。 A.使帧频增高 B.降低血流成像的

题型:单项选择题 A型题

问题:

彩色多普勒的取样框调节过大,会出现的现象是()。

A.使帧频增高

B.降低血流成像的敏感性

C.使血流方向不易判断

D.使血流速度提高

E.增加血流成像的敏感性

考点:医技考试超声波医学与技术(主管技师)超声波医学与技术相关专业知识考前冲刺三
题型:单项选择题 A型题

It seems impossible to have an honest conversation about global warming. I say this after diligently perusing the British government’s huge report released last week by Sir Nicholas Stern, former chief economist of the World Bank and now a high civil servant. The report is a masterpiece of misleading public relations. It foresees dire consequences if global warming isn’t curbed: a worldwide depression and flooding of many coastal cities. Meanwhile, the costs of minimizing these awful outcomes are small: only 1 percent of world economic output in 2050.

No sane person could fail to conclude that we should conquer global warming instantly, if not sooner. Who could disagree Well, me. Stem’s headlined conclusions are intellectual fictions. They’re essentially fabrications to justify an aggressive anti-global-warming agenda. The danger of that is that we’d end up with the worst of both worlds: a program that harms the economy without much cutting of greenhouse gases.

Let me throw some messy realities onto Stern’s tidy picture. In the global-warming debate, there’s a big gap between public rhetoric and public behavior. Greenhouse emissions continue to rise despite many earnest pledges to control them. Just last week, the United Nations reported that of the 41 countries it monitors (not including most developing nations), 34 had increased greenhouse emissions from 2000 to 2004. These include most countries committed to reducing emissions under the Kyoto Protocol.

Why is this In rich democracies, policies that might curb greenhouse gases require politicians and the public to act in exceptionally "enlightened" ways. They have to accept "pain" now for benefits that won’t materialize for decades, probably after they’re dead. And even if rich countries cut emissions, it won’t make much difference unless poor countries do likewise and so far, they’ve refused because that might jeopardize their economic growth and poverty-reduction efforts.

The notion that there’s only a modest tension between suppressing greenhouse gases and sustaining economic growth is highly dubious. Stern arrives at his trivial costs—that 1 percent of world GDP in 2050—by essentially assuming them. His estimates presume that, with proper policies, technological improvements will automatically reconcile declining emissions with adequate economic growth. This is a heroic leap. To check warming, Stern wants annual emissions 25 percent below current levels by 2050. The IEA projects that economic growth by 2050 would more than double emissions. At present, we can’t bridge that gap.

The other great distortion in Stern’s report involves global warming’s effects. No one knows what these might be, because we don’t know how much warming might occur, when, where, or how easily people might adapt. Stern’s horrific specter distills many of the most terrifying guesses, including some imagined for the 22nd century, and implies they’re imminent. The idea is to scare people while reassuring them that policies to avert calamity, if started now, would be fairly easy and inexpensive.

The author agrees with Stern that()

A. global warming is something to fight with

B. curbing global warming will not affect economy

C. an aggressive anti-global-warming agenda is necessary

D. not much cost will be involved in conquering global warming

题型:单项选择题 A型题

教育心理学不仅要研究如何有效地学与有效地教,而且要研究教育的科学内容。()

题型:单项选择题 A型题

精车时,为减小()与工件的摩擦,保持刃口锋利,应选择较大的后角。

A.基面

B.前刀面

C.后刀面

D.主截面

题型:单项选择题 A型题

友好交往礼为先,礼貌是交往的“名片”。下列关于礼貌的说法正确的是[ ]

①礼貌是尊重的具体表现

②礼貌是文明的体现

③礼貌反映一个人的素质,展示一个人的风采

④有了礼貌,就有了与人交往的亲和力

A.①②③

B.②③④

C.①②③④

D.①②④

题型:单项选择题 A型题

You are not helping your child if you try to()him from every danger.

A.avoid

B.shade

C.shield

D.conceal

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