阅读理解。
Michael Fish may soon be replaced as a weather forecaster by something truly fishier---the shark (鲨鱼).
Research by a British biology student suggests that sharks could be used to predict storms.
Lauren Smith, 24, is close to completing her study on shark's ability to sense pressure.
If her studies prove the theory, scientists may be able to monitor the behaviour of sharks to predict bad
weather.
Miss Smith had previously studied the behaviour of lemon sharks in the Bahamas.
She then used their close relatives, lesser spotted dogfish, for further research at Aberdeen University.
Her work---thought to be the first of its kind to test the pressure theory ---- resulted from the observation
that juvenile blacktip sharks off Florida moved into deeper water ahead of a violent storm in 2001.
Miss Smith said: "I've always been crazy about traveling and diving and this led me to an interest in sharks."
"I was delighted to have been able to research in the area for my degree. I know there's so much more we
need to understand ---- but it certainly opens the way to more research."
It has been discovered that a shark senses pressure using hair cells in its balance system.
At the Bimini Shark Lab in the Bahamas, Miss Smith fixed hi-tech sensors to sharks to record pressure and
temperature, while also tracking them using GPS (Global Positioning System) technology.
In Aberdeen, she was able to study the effects of tidal (潮汐的) and temperature changes on dogfish----
none of which were harmed. She also used a special lab which can mimic (模拟) oceanic pressure changes
caused by weather fronts.
She is due to complete her study and graduate later this year. She says she will be looking for a job which
will give her the chance to enrich her experience of shark research.
1. The passage is most probably taken from _____.
A. a short-story collection
B. a popular science magazine
C. a research paper
D. a personal diary
2. What do we learn from the first four paragraph of the passage?
A. Sharks may be used to predict bad weather.
B. Sharks' behaviour can be controlled.
C. Michael Fish is not qualified for his job.
D. Lauren Smith will become a weather forecaster.
3. Lauren Smith conducted her research by _______.
A. removing hair cells from a shark's balance system
B. measuring the air pressure of weather fronts
C. recording sharks' body temperature
D. monitoring sharks' reaction to weather changes
4. What is the passage mainly about?
A. A popular way of forecasting weather.
B. A new research effort in predicting storms.
C. Biologists' interest in the secrets of sharks.
D. Lauren Smith's devotion to scientific research.
，刚启动时速度v较小，牵引力F大，列车做加速运动，速度v越来越大，牵引力F越来越小，根据牛顿第二定律F=ma，加速度越来越小，AD选项错误，B选项正确。当牵引力减小到等于阻力时，物体所受合力为0，做匀速直线运动，速度不会减小，C选项错误。