阅读下面的短文。每篇短文的后面有五个问题，每个问题有四个备选答案。请根据短文的内容选择最佳答案。每个试题计3分,共计15分。
A device that provides early warning of a landslide by monitoring vibrations in soil is being tested by UK researchers. Tile device could save thousands of lives each year by warning when an area should be evacuated，the scientists say. Such natural disasters are common in countries that experience sudden，heavy rainfall，and can also be triggered by earthquakes and even water erosion.
The most common way to monitor a slope for signs of an imminent landslide is to watch for changes in its shape.Surveyors can do this by measuring a site directly，or sensors sunk into boreholes or fixed above ground can be used to monitor the shape of a slope.Slopes can，however，change shape without triggering a landslide，so either method is prone to causing false alarms.Now Dixons team has developed a device that listens for the vibrations caused when particles begin moving within a slope.
The device is currently being tested in a 6-metre-tall artificial clay embankment in Newcastle2，UK.Early results suggest it should provide fewer false positives than existing systems.Once it has been carefully and thoroughly tested，the device could be used to create a complete early-warning system for dangerous slopes.
词汇：5lAndslaId5iminEntp
vibrationn.振动 sensor n.传感器
rainfalln.降雨，降雨量 graveln.砾，沙砾，砾石
注释：
2. Newcastle：纽卡斯尔。英格兰东北部的一个自治区，位于利兹以北泰纳河畔。
1. What does Such natural disasters in the first paragraph refer to?
B Earthquakes.
D Landslides.
A The initial movement is hard to spot.
C They can be destructive in a matter of hours or minutes.
3. Why do researchers develop a new device to monitor signs of landsides?
B Because the new device can be sunk into boreholes or fixed above ground.
D Because the common methods are useless.
A It is filled in with gravel.
C It is dropped into a horehole filled in with gravel.
5. According to the context，what does the word positives in the fifth paragraph mean?
B Evidences.
D Predictions.
1. D 短文第一段的第一句告诉我们，英国研究人员正在测试一种仪器，这种仪器可以通过监测土壤的振动来预警山崩。该段最后一句说，这种灾难经常在一些遭受自然灾害的国家发生，这些自然灾害包括sudden，heavy rainfall和earthquakes以及water erosion。所以D是正确选择。
3. C 第三段的第一和第二句告诉我们，最为普通的监测山崩方法是对山坡形状变化的观察，有两种观察方式;第三句说，因为山坡形状的变化不一定导致山崩，所以两种方法都会有虚假的预警。因此，C是正确答案。
5. B positives在此用作名词，意思是：被证实的因素或特点，可以理解为证据。