You may never be in an emergency situation. But if it happens, you should know how to get help. The telephone book in the United States has emergency numbers on the inside front cover. Look at the following table from the Boston telephone book. Notice that the numbers for the police and the fire department (部门) are the same. And it is an easy number to remember. If you are too unhappy or excited to remember any numbers at all, you can simply dial (拨打) “0” for an operator (接线员) in any emergency.

以下各组性状中，属于相对性状的是（　　）

  $\frac{3}{5}$ 千克表示把3千克平均分成____份，取其中的____份，每份是____千克；也表示把____千克平均分成____份，，取其中的____份，每份是____千克。