点(1,1)在圆(x-a)2+(y+a)2=4内,则实数a的取值范围是________.
(-1,1)
∵点(1,1)在圆的内部,∴(1-a)2+(1+a)2<4,∴-1<a<1.
One of the effective ways to lessen environmental pollution is the reservation and protection of more swamps.
A.vast thick corals
B.pockets of wetland
C.warm volcanoes
D.millions of bees and wasps
心传导系统的分支蒲肯野氏纤维存在于:()。
A.心内膜
B.心肌膜
C.心瓣膜
D.心内膜下层
E.心外膜