A:≤3
B:<3
C:≥3
D:>3
It will be 20 years since Hong Kong returned to China on July 1,1997.(就划线部分提问)
____ ____years will it be since Hong Kong returned to China on July 1, 1997?
“科学用眼,保护视力”是青少年珍爱生命的具体表现.科学证实:近视眼镜的度数y(度)与镜片焦距x(m)成反比例.如果500度近视眼镜片的焦距为0.2m,则表示y与x函数关系的图象大致是( )
如图,AB是⊙O的直径,CD为弦,CD⊥AB且相交于点E,则下列结论中不成立的是( )