I. Multiple choice questions
1. Let A={ 1, 2, 3, 4, 5, 6, 7, 8}, R is the divisible relation on A, and B={2, 4, 6}, then the largest element, smallest element, upper bound and lower bound of set B are (D. None.
A: 8.2, 8.2
8， 1，6， 1
C.6，2，6，2
D. no, 2, no, 2
2. Let the function on the set A={ 1, 2,3} be:
f = { & lt 1，2 & gt； ，& lt2， 1 & gt； ，& lt3，3 & gt； }，g = { & lt 1，3 & gt； ，& lt2，2 & gt； ，& lt3，2 >},
h = { & lt 1，3 & gt； ，& lt2， 1 & gt； ，& lt3， 1 & gt； }, then h=(B.g? f)。
A.f？ g
B.g？ f
C.f？ f
D.g？ g
3. Let the binary relation r = {< 1,1> ，& lt2，2 & gt； ，& lt2，3 >，& lt4，4 >}，S = { & lt 1， 1 & gt； ，& lt2，2 & gt； , & lt2,3 >, & lt3,2 >,<4 >}, then S is a (b.transitive) closure of R. 。
A. reflexivity
B. Pass on
C. symmetry
D. reflexivity and transmission
4. if the set A={ 1, 2, 3, 4, 5, 6, 7, 8} R = {< x, y & gt|x+y= 10 and x and y belong to A}, then the property of r is (b) symmetric.
A. reflexive
B. symmetrical
C. transitive symmetry
D. reflexive and transitive
5. Let the set A={ 1, a}, then P(A)=(D.{ empty set, {1}, {a}, {1, a}}).
A.{{ 1}，{a}}
B.{ empty set, {1}, {a}}
C.{{ 1}，{a}，{ 1，a}}
D.{ empty set, {1}, {a}, {1, a}}
6. Let the set A={a}, then the power set of A is (C.{ empty set, {a}}).
A.{{a}}
B.{a，{a}}
C.{ empty set, {a}}
D.{ empty set, a}
7. If the number of elements in set A is 10, the number of elements in its power set is (A. 1024).
A. 1024
10
C. 100
D. 1
8. Set A={ 1, 2,3,4 4} R = {
A. non-reflective
B. Asymmetry
C. transitional
D. reflexivity
9. Let A={a, b, c}, B={ 1, 2} and f: a → b, then the number of different functions is (d.8).
A.2
B.3
C6
D.8
10. If the set A = {1 2}, B = {1 2, {1 2}}, then the following statement is correct: (A.A belongs to B and A is included in B).
A.A belongs to b, and a is contained in B.
B.b belongs to a, and a is contained in B.
C.A does not belong to B. A is included in B.
D.A does not belong to B. A is not included in B.