下列哪一组是相对性状?( )
①单眼皮和双眼皮 ②有耳垂和无耳垂 ③能卷舌和不能卷舌
④卷发与黑发 ⑤双眼皮与色盲 ⑥头发左旋与惯用右手.
A:①②④
B:①②③
C:①②⑤
D:①③④
若函数f(x)的零点与g(x)=lnx+2x﹣8的零点之差的绝对值不超过0.5,则f(x)可以是( )
阅读短文,选择正确的答案。
There is a park near our school. Wecan see many trees and flowers there. Some flowers are red, and some areyellow. We can see a hill behind the park too. At the foot of the hill we cansee a river. There are some boats on it. Children like to go there. It is springnow. There are many children in the park. Some are walking and singing. Some aredancing and playing games. Ann and her sister Kate are flying a kite. Tom andhis brother Sam are throwing a frisbee(飞盘).Their father and mother are sitting under the tree. They are all happy.
按要求画图.
(I)绕A点将三角形逆时针旋转90°,再向右平移5格.
(II)在方格中画一个平行四边形使它的面积是已知三角形面积的2倍.
双曲线x2a2-y2b2=1a>0,b>0的左右焦点为,F1,F2,P是双曲线上一点,满足|PF2|=|F1F2|,直线PF1与圆x2+y2=a2相切,则双曲线的离心率为( )