=IF(ISNA(MATCH(A3,$B$3:$B$1904,0)),VLOOKUP(A3,$B$3:$B$1904,5,FALSE)),

=IF(ISNA(MATCH(A3,$B$3:$B$1904,0)),VLOOKUP(A3,$B$3:$B$1904,5,FALSE)),
=IF(ISNA(MATCH(A3,$B$3:$B$1904,0)),VLOOKUP(A3,$B$3:$B$1904,5,FALSE)),

=IF(ISNA(MATCH(A3,$B$3:$B$1904,0)),VLOOKUP(A3,$B$3:$B$1904,5,FALSE)),
公式有错误,应该为：
=IF(ISNA(MATCH(A3,$B$3:$B$1904,0)),"",VLOOKUP(A3,$B$3:$F$1904,5,FALSE)),
1、MATCH(A3,$B$3:$B$1904,0),在$B$3:$B$1904找不到A3相同的数据,找到返回序号,否则出错；
2、用ISNA判断第1步的结果是否为错,错时为真,已经TRUE；
3、VLOOKUP(A3,$B$3:$F$1904,5,FALSE),在$B$3:$B$1904查找A3,找到后返回F列对应的数据；
4、总体公式的含意：在$B$3:$B$1904中查找不到A3时为空,否则,得到同行F列的数据.