A.3个 | B.2个 | C.1个 | D.0个 |
A.存在x0∈R,使得的否定是:不存在x0∈R,使得; |
B.存在x0∈R,使得的否定是:任意x∈R,均有 |
C.若x=3,则x2-2x-3=0的否命题是:若x≠3,则x2-2x-3≠0. |
D.若为假命题,则命题p与q必一真一假 |
A.:$,,且为假命题 |
B.:$,,且为真命题 |
C.:",,且为假命题 |
D.:",,且为真命题 |
A.若x,y∈R且x2+y2≠0,则x,y全不为0 |
B.若x,y∈R且x2+y2≠0,则x,y不全为0 |
C.若x,y∈R且x,y全为0,则x2+y2=0 |
D.若x,y∈R且x,y不全为0,则x2+y2≠0 |
© 2017-2019 超级试练试题库,All Rights Reserved.