数据如下：

 2008/11/18   18:40:17.6    19.22     110.82      10     ML2.4     6      海南琼海近海
QXL                                                      0.10     SME       2.600     
QXL   179.5                     SG    18:41:11.1  ML2.3  0.10     SMN       2.800     
QXL                             PG    18:40:49.7                                      
NDA                                                      0.10     SME       5.800     
NDA   135.2                     SG    18:40:58.4  ML2.3  0.10     SMN       8.600     
NDA                             PG    18:40:41.9                                      
QZH                                                      0.10     SME       46.900    
QZH                             PG    18:40:26.7                                      
QZH   49.8                      SG    18:40:32.6  ML2.6  0.10     SMN       73.400    
QZN                                                      0.10     SME       5.100     
QZN   105.1                     SG    18:40:49.8  ML2.2  0.10     SMN       9.600     
QZN                             PG    18:40:37.3                                      
SYA                                                      0.10     SME       2.600     
SYA   179.5                     SG    18:41:11.1  ML2.3  0.10     SMN       2.800     
SYA                             PG    18:40:49.7                                      
QXL                                                      0.10     SME       31.600    
QXL   98.7                      SG    18:40:46.0  ML2.8  0.10     SMN       43.500    
QXL                             PG    18:40:34.8                                      
DAN                                                      0.10     SME       10.400    
DAN   72.2                      SG    18:40:40.2  ML2.4  0.20     SMN       15.100    
DAN                             PG    18:40:31.3                                      
QSL                                                      0.10     SME       46.900    
QSL                             PG    18:40:26.7                                      
QSL   49.8                      SG    18:40:32.6  ML2.6  0.10     SMN       73.400    
 2008/11/18   03:05:04.1    19.20     110.83      10     ML2.8     6      海南琼海近海
QXL                                                      0.20     SME       3.300     
QXL   180.1                     SG    03:05:58.2  ML2.6  0.20     SMN       4.000     
QXL                             PG    03:05:36.2                                      
NDA                                                      0.10     SME       5.300     
NDA   137.7                     SG    03:05:45.4  ML2.6  0.20     SMN       10.100    
NDA                             PG    03:05:28.9                                      
QZH                             PG    03:05:13.6                                      
QZH                                                      0.10     SME       92.400    
QZH   51.9                      SG    03:05:19.4  ML2.8  0.10     SMN       114.100   
QZN                                                      0.20     SME       6.400     
QZN   106.9                     SG    03:05:37.3  ML2.4  0.10     SMN       9.300     
QZN                             PG    03:05:24.2                                      
SYA                                                      0.20     SME       3.300     
SYA   180.1                     SG    03:05:58.2  ML2.6  0.20     SMN       4.000     
SYA                             PG    03:05:36.2                                      
QXL                                                      0.10     SME       66.200    
QXL   100.9                     SG    03:05:33.1  ML3.1  0.10     SMN       88.500    
QXL                             PG    03:05:21.7                                      
DAN                                                      0.20     SME       16.300    
DAN                             PG    03:05:18.3                                      
DAN   75.0                      SG    03:05:27.2  ML3.0  0.20     SMN       53.800    
QSL                             PG    03:05:13.6                                      
QSL                                                      0.10     SME       92.400    
QSL   51.9                      SG    03:05:19.4  ML2.8  0.10     SMN       114.100   
 2008/11/07   21:07:09.0    19.48     108.73      10     ML2.3     6      海南昌江近海
   
    请问该如何获得中间部分，即以英文字母开头的数据行数