How to insert several lines into internal tables from other internal tables? | SAP-ABAP

=>  The following statement is used to add several lines into internal tables from other internal table:
INSERT LINES OF <itab> INTO <Ptab> [INDEX <idx>].
 This statement inserts the lines of table <itab> one by one into <ptab>
When an index table is appended to another index table, the lines are specified as follows:
 INSERT LINE OF <itab> [FROM <n1>] [TO <n2>] INTO <ptab> [INDEX <idx>].
<nl > and <n2 > specify the indexes of the first and last lines of ITAB that is to be inserted into PTAB.