关于互成角度的两个初速度不为零的匀变速直线运动的合运动，下属_爱下问搜题

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问题选择题

关于互成角度的两个初速度不为零的匀变速直线运动的合运动，下属说法正确的是：

A．一定是直线运动

B．一定是抛物线运动

C．可能是直线运动，也可能是曲线运动

D．以上说法都不对

答案

答案：C

题目分析：由物体做曲线运动的条件可知，当两个初速度的合初速度V，两个加速度的合加速度a，V与a共线时为匀变速直线运动，V与a不共线时，为匀变速曲线运动，故选C

点评：互成角度的两个初速度不为零的匀变速直线运动的合运动，是怎样的运动？判断方法：是根据两个初速度的合初速度V，两个加速度的合加速度a，V与a共线时为匀变速直线运动，V与a不共线时，为匀变速曲线运动来判断的．

单项选择题

早期下咽癌的症状是()

A．咽异物感、吞咽隐痛

B．音哑

C．吞咽困难

D．咳嗽、气短

E．双颈淋巴结肿大

完形填空

A group of graduates got together to visit their old university professor.
The conversation soon turned into complaints about ____ in work and life. Offering his__ coffee, the professor went to the kitchen and ____ with a large pot of coffee and a ____ of cups---porcelain(陶瓷), plastic, glass, crystal(水晶), some plain-looking, some expensive, some beautiful—telling them to ____ themselves to the coffee.
When all the students had a cup of coffee in hand, the professor said,“If you have ____all the nice-looking expensive cups have been ____, leaving behind the plain and ____ ones. While it is normal for you to want only the best for yourselves , that is the ____ of your problems and stress.”
“Be assured that the cup ____ adds no quality to the coffee. ____ it is just more expensive and in some cases ____ hides what we drink.”
“____ all of you really want is coffee, not the cup, ____ you consciously went for the best cups…. And then you began ____ each other’s cups.”
Now consider this:__ __ is the coffee; the jobs, money and position in society are the cups. ____ are just tools to hold and contain life, and the type of cup we have does not define, nor change the ____ of life we live. Sometimes , by concentrating only on the cup, we ____ to enjoy the coffee. Value the coffee, not the cups! Don’t let the cups ____ you...enjoy the coffee instead.

D．In most cases