Modern life is impossible without traveling. The fastest way of traveling is by plane. With a modern plane it takes one day to travel places which took a month or more to get to a hundred years ago.
Traveling by train is slower than by plane, but it has its advantages（优势）. You can see the country you are traveling through. Modern trains have comfortable seats and dining-cars. They make even the longest journey enjoyable.
Some people prefer to travel by sea when possible. There are large planes and river boats. You can visit many other countries and different parts of your country on them. Ships are not as fast as trains or planes, but traveling by sea is a very pleasant way to spend a holiday.
Many people like to travel by car. You can make your own timetable. You can travel three or four hundred miles or only fifty or one hundred miles a day, just as you like. You can stop wherever you wish --- where there is something interesting to see, at a good restaurant where you can enjoy a good meal, or at a hotel where you can spend the night. That is why traveling by car is a popular pleasant trip, while people usually take a train or a plane when they are traveling on business.
小题1:From the passage (短文), we know the fastest way of traveling is ____.
A．by train
B．by sea
C．by plane
D．by car小题2:If we travel by car, we can _____.
A．make the longest journey enjoyable
B．travel to a very far place in several minutes
C．make our own timetable
D．travel only fifty or one hundred miles a day小题3:The underlined (划线的) word “They” in the passage refers to (指的是)____.
A．modern trains in the country
B．comfortable seats and dining-cars
C．the travelers on the modern trains
D．the slower ways of traveling小题4:When people travel on business, they usually take ____.
A．a plane or a car
B．a car or a boat
C．a boat or a train
D．a train or a plane小题5: How many ways of traveling are mentioned (被提到的) in the passage?
A．Four.
B．Three.
C．Two.
D．Six
的输出结果与（34） 等价，该表达式与 （35） 等价。若对关系 R、S 进行自然连接，所得关系的属性列数和元组个数分别为 （36） 。 
