I have two list, just like
a={a1,a2,a3,a4};
b={b1,b2,b3,b4,b5};
I want merge them and save to excel, as they have different dimention, so I want it have the following format.
{{a1,b1},{a2,b2},{a3,b3},{a4,b4},{null,b5}}
and in the excel it will leave blank or fill some special words in the miss information position.