问题 单项选择题

下列叙述中正确的是

A.线性链表是线性表的链式存储结构

B.栈与队列是非线性结构

C.双向链表是非线性结构

D.只有根结点的二叉树是线性结构

答案

参考答案:A

解析: 一个非空的数据结构如果满足下列两个条件:(1) 有且只有一个根结点;(2) 每一个结点最多有一个前件,也最多有一个后件;则称为线性结构。线性链表是线性表的链式存储结构,选项A的说法是正确的。栈与队列是特殊的线性表,它们也是线性结构,选项B的说法是错误的。双向链表是线性表的链式存储结构,其对应的逻辑结构也是线性结构,而不是非线性结构,选项c的说法是错误的。二叉树是非线性结构,而不是线性结构,选项D的说法是错误的。因此,本题的正确答案为A。

选择题
阅读理解

阅读理解

     In America, drivers' education is part of the regular high school curriculum. Every student in his or her

second year of high school is required to take a class in driver's education. However, unlike other courses, it is not given during the regular school year. Instead it is a summer course.

     The course is divided into two parts: class time for learning laws and regulations and driving time to

practice driving. Class time is not unlike any other class. The students have a text from which they study the basic laws they must know to pass the written driving test that is given to anyone wanting to get a driver's

license(驾照).

     Driving time is a chance for the students to get behind the wheel(steering wheel) and practice starting,

steering(驾驶), backing up, parking, switching lanes, turning corners, and all the other maneuvers(操作)

required to drive a car. Each student is required to drive a total of six hours. The students and the

instructor go out driving for two-hour blocks of time. Thus, each student gets half an hour driving time

per outing. The instructor and "driver" sit in the front seats and the other three students sit in the back.

     Drivers Ed cars are unlike other cars in which they have two sets of brakes(刹车), one on the driver's

side and one on the other side where the instructor sits. Thus, if the student driver should run into

difficulties the instructor can take over. The car also has another special feature. On the top of the car is a

sign that reads: STUDENT DRIVER. That lets nearby drivers know that they should use extra caution

(谨慎)because the student driver is a beginning driver, not very experienced and prone to(易于…的)

driving slowly.

     After the student has passed the driver's education course and reached the appropriate(适当的)age to drive(this age differs in every state but in most cases the person must be 16 years old), they can go to a

designated(指定的)state office to take their driver's test, which is made up of an eye examination, a

written test, and a road test. The person must pass all the three tests in order to be given a driver's license. If the person did well in his or her driver's education class, he or she will pass the test with flying colors a

nd get a driver's license.

1. In America, the driver's course mentioned above is ________.

A. considered as part of the advanced education

B. given to anyone wanting to get a driver's license

C. carried on at the same time as other courses

D. required of all the students of Grade 2 in high schools

2. To prevent accidents, a driver's ED car ________.

A. has a sign inside it

B. has two sets of brakes

C. is big enough to hold five persons

D. can't run very fast

3. We can infer that the students are required to ________ in their whole driving practice.

A. go out driving for twelve times

B. spend at least six hours driving

C. drive for two-hour blocks of time

D. get half an hour driving

4. Which of the following does not agree with the requirements for the students wanting to get their driver's license?

A. They must be 16 years of age.

B. They should go to have their driver's course.

C. They must have their eyes examined.

D.They ought to do well in their driver's course.

5. In the last sentence, "with flying colors" means _________.

A. happily

B. successfully

C. colorfully

D. quickly