回複：急問,家國技術移民申請,一定要有cover letter嗎?

You always need cover letter for almost all communications. It is easily written, you can say something like this:

Dear officer,

With this letter I am applying the canada immigration
under catagory of skilled work. (Add spouse or kids here as dependents if there any). Inclosed with letter
please find the following documents;
(list all documents in good orders, e.g., summary of
qulification, education documents, ...).

Please notify us for any other necessary documents. And
we are looking forward to hear from your office.

-