关键词越多，排得越前
比如下表，sentence里面匹配关键词in和James，最多的是id=10其次是id=7和id=9
ID sentence AGE ADDRESS
1 Paul in run 32 California 20000.0
2 Allen sa 25 Texas 15000.0
3 Teddy dad 23 Norway 20000.0
4 Mark 25 Rich-Mond 65000.0
5 David 27 Texas 85000.0
6 Kim 22 South-Hall 45000.0
7 James ad 24 Houston 10000.0
8 Paul 24 Houston 20000.0
9 James 44 Norway 5000.0
10 James in 45 Texas 5000.0
