【单选题】【消耗次数：1】
设一平面图G有 n个顶点, m 条边, r 个面，k个连通分支，则下列哪个是欧拉公式：
①
m - n + r = 2；
②
n - m + r = k + 1；
③
n - r + m = k + 1；
④
n - m + r = 2。
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【多选题】
设一平面图G有 n个顶点, m 条边, r 个面，k个连通分支，则下列哪些不是欧拉公式：
①
m - n + r = 2；
②
n - m + r = k + 1；
③
n - r + m = k + 1；
④
n - m + r = 2。
【多选题】
设 G*是具有 k(k 3 2)个连通分支的平面图 G 的对偶图, n*, m*, r* 和 n, m, r 分别为 G*和 G 的顶点数, 边数, 面数, 则下面哪个式子正确：
①
n* = r;
②
m* = m;
③
r* = n - k + 1;
④
r* = n 。
【单选题】
设 G*是具有 k(k 3 2)个连通分支的平面图 G 的对偶图, n*, m*, r* 和 n, m, r 分别为 G*和 G 的顶点数, 边数, 面数, 则下面哪个式子不正确：
①
n* = r;
②
m* = m;
③
r* = n - k + 1;
④
r* = n 。
【多选题】
设一连通平面图G有 n个顶点, m 条边, r 个面，则下列哪些不是欧拉公式：
①
m - n + r = 2；
②
n - m - r = 2；
③
n - r + m = 2；
④
n - m + r = 2。
【判断题】
设 G*是连通平面图 G 的对偶图, n*, m*, r* 和 n, m, r 分别为 G*和 G 的顶点数, 边数, 面数, 则 r* = n - 2。
①
正确
②
错误
【单选题】
设 G*是连通平面图 G 的对偶图, n*, m*, r* 和 n, m, r 分别为 G*和 G 的顶点数, 边数, 面数, 则下面哪个式子不正确：
①
n* = r;
②
m* = m;
③
r* = n - 2;
④
r* = n 。
【单选题】
设G是 n（n≥3)阶m 条边的简单平面图，则下列哪个公式是正确的：
①
m - n + r = 2；
②
m ≤ 2n - 4；
③
m ≤ 3n - 6；
④
m ≤ 4n - 8。
【单选题】
若关系R和S分别有r和s个属性，分别含有m和n个元组，则R×S（ ）
①
包含r+s个属性和m+n个元组
②
包含r+s个属性和m×n个元组
③
包含r×s个属性和m+n个元组
④
包含r×s个属性和m×n个元组
【单选题】
若关系R和S分别有r和s个属性，分别含有m和n个元组，则R×S（ ）
①
A.包含r+s个属性和m+n个元组
②
B.包含r+s个属性和m×n个元组
③
C.包含r×s个属性和m+n个元组
④
D.包含r×s个属性和m×n个元组
【单选题】
已知 n 阶 m 条边的无向图 G 是 k(k 3 2)棵树组成的森林， 则有：
①
m = n-1;
②
m = n-k;
③
n-m+k=2;
④
2m = n + k。
随机题目
【单选题】
Which of the following is true about pronunciation teaching?
①
Learners whose native language has similar sounds are less likely to have problems with pronunciation
②
Learners who have more exposure to English need less focus on pronunciation
③
Beginning Chinese learners of English need a certain degree of focus on pronunciation
④
All of the above.
【单选题】
Which of the following do not belong to minimal pair?
①
Will well
②
Till tell
③
Fill fell
④
Well well.
【单选题】
What are the ways of practicing stress?
①
Use gestures
②
Use the voice
③
Use the blackboard
④
All of the above.
【单选题】
Which of the following belong to pronunciation perception practice?
①
using minimal pairs, odd one out
②
Which order, completion
③
Same or different
④
All of the above.
【单选题】
Which of the following is the time when students work as a whole class?
①
When all the students are under the control of the teacher
②
When students work in pairs on an exercise or a task
③
When students work in small groups
④
When students are expected to work on their own at their own speed.
【单选题】
What role does a teacher play in the following activity? While doing a writing task either individually or in groups, the students need to use a particular word they don’t know. So they ask the teacher.
①
Controller
②
Assessor
③
participant
④
Resource-provider.
【单选题】
What role does a teacher play in the following activity? The teacher asks a student a question “Have you ever bought clothes with problems?” If the student doesn’t seem to be ready, the teacher says “for example, a shirt without...” and points to the buttons on his own shirt or jacket.
①
Controller
②
Assessor
③
Organizer
④
Prompter.
【单选题】
What role does a teacher play in the following activity? T: do you have any hobbies? S: yes, I like singing and dancing. T: Uhm, and...? S: I also collect coins. T: Oh, really, how many...have you already...collected?
①
Controller
②
Assessor
③
Organizer
④
Prompter
【单选题】
Which of the following is the advantage of whole class work?
①
It is an ideal way to show materials and do presentations together
②
It allows students to work together rather than under teacher’s guidance.
③
There is always a great chance of different opinions and contributions to the work
④
It is less stressful.
【单选题】
Which of the following is the time when students work in groups?
①
When all the students are under the control of the teacher
②
When students work in pairs on an exercise or a task
③
When students work in small group
④
When students are expected to work on their own at their own speed.