After you hear a question, you must choose the best answer from the four choices marked A, B, C and D.

听到问题后，必须从A、B、C、D四个选项中选出最佳选项。

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For each of them there are four choices marked A, B, C and D. You should decide on the best choice and mark the corresponding letter on Answer Sheet 2 with a single line through the centre.

每题都有对应标记的A、B、C和D四个选项，请选择最佳选项并在答题卡2的相应字母中间划横线。

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All four C-130s based in Elizabeth City, N.C., are flying on patrols on Friday, but will move inland as far as West Virginia as the storm approaches.

4架驻扎在北卡罗莱纳州伊丽莎白市的c - 130运输机在周五参与了巡逻飞行，但会在风暴来临前转移到更远的西弗吉尼亚。

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Since two thousand five, the F.C.C.has used four policy principles to guide its enforcement in cases related to the Internet.

VOA: special.2009.09.25

And the last example that we're going to talk about is thionyl chloride, so it's s o c l 2. This is another good step forward, because now we actually have four different atoms in our molecule.

我们要讨论的最后一个例子,是氯化亚砜，就是硫，氧，氯，二，这又是一个进步，因为我们的分子中现在有四个不同的原子了。

麻省理工公开课 - 化学原理课程节选

So carbon has four valence electrons, so if we talk about c 2, again we're going to start filling in our molecular orbitals, and now we're going to have eight electrons to fill into our molecular orbitals.

碳有4个价电子，所以如果我们考虑C2的话，同样，我们开始填分子轨道，现在我们有8个电子,要填入分子轨道。

麻省理工公开课 - 化学原理课程节选

To overcome this problem, the researchers looked at four hepatitis C epidemics in Greece, using data from 943 patients collected between 1995 and 2000.

BBC: Spread of hepatitis C pinpointed

And the modernisation plans comes as the UK is increasing its ability to deploy forces abroad, with six new roll-on, roll-off ferries, and the leasing of four giant C-17 cargo planes, leased from the Americans, which can carry Apache attack helicopters or Chinooks around the world.

BBC: NEWS | UK | The armed forces of the future

The four-engine C-17 jet can land on a runway only 3, 000 feet long and 90 feet wide, according to a document from the Department of Defense.

CNN: U.S. may sedate Afghan detainees during flights