Here's a reading test that I did the other day:
Dear Mr. Prosser,
The information that you requested about changes to the hunting permit scheme has been enclosed. Please note that each permit must be filled out and applied for separately. When filling out your application, you must mark all answers clearly and with a black or blue pen. Please do not use cursive script, print only. Each application ______ enclosed in its own envelope and received before the applicable deadline. Received applications can take up to 5 weeks to process. Because of this, you must plan your submissions in a timely fashion to make sure that you receive your permit while the applicable season is still open. I hope that the information enclosed answers all of your questions. Take care and happy hunting.
I'm not sure why the answer says it should be "would be" in the blank, not "must be". In my opinion, must be is a more suitable answer since the whole mail is sort of telling the guy what to do in a relatively strong tone.