fix grammer

docs/en/12-taos-sql/06-select.md

@@ -183,7 +183,7 @@ select _rowts, max(current) from meters;
 
 **\_IROWTS**
 
-The \_IROWTS pseudocolumns can only be used with INTERP FUNCTION. This pseudocolumns can be used to retrieve the corresponding timestamp column associated with the INTERPOLATION results.
+The \_IROWTS pseudocolumn can only be used with INTERP function. This pseudocolumn can be used to retrieve the corresponding timestamp column associated with the interpolation results.
 
 ```sql
 select _irowts, interp(current) from meters range('2020-01-01 10:00:00', '2020-01-01 10:30:00') every(1s) fill(linear);