已知⊙O1与⊙O2的半径分别为2和3,若两圆相交,则圆心距d的取值范围是__________.
1<d<5
解:∵两圆相交,∴3-2<d<3+2,即1<d<5.
故选D
I traveled ______ the world for a few years. [ ]
A. all
B. on
C. for
D. around
储蓄的实质是()。