A.如果命题“¬p”与命题“p或q”都是真命题,那么命题q一定是真命题; | ||
B.命题“若a=0,则ab=0”的否命题是:“若a≠0,则ab≠0”; | ||
C.若命题p:∃x∈R,x2-x+1<0,则¬p:∀x∈R,x2-x+1≥0; | ||
D.“sinθ=
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1 |
2 |
A.4个 | B.3个 | C.2个 | D.1个 |
A.命题“∀x∈R,2x>0”的否定是“∃x0∈R,2x0≤0” | ||||
B.命题“若xy=0,则x=0”的否命题为“若xy≠0,则x≠0” | ||||
C.“sinα=
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D.函数y=2x-3+1的图象恒过定点A(3,2) |
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