a |
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c |
a |
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c |
c |
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0 |
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a |
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a |
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a |
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0 |
A.①②③ | B.②③④ | C.①③④ | D.①②③④ |
c |
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c |
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c |
a |
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b |
c |
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c |
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0 |
A.1 | B.2 | C.3 | D.4 |
A.∀x∈R,x2>0 | B.∀x∈Q,x2∈Q |
C.∃x0∈Z,x02>1 | D.∀x,y∈R,x2+y2>0 |
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a |
b |
A.若命题p:∃x∈R,x2-x+1=0,则¬p:∀x∈R,x2-x+1≠0 | ||
B.命题“若a=0,则ab=0”的否命题是:“若a≠0,则ab≠0” | ||
C.“sinθ=
| ||
D.若命题“¬p”与命题“p或q”都是真命题,那么命题q一定是真命题 |
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