Do you have a pen?I want _____ a letter.   

 You are too tired, please stop _______.

In the old days, people lived in caves and they had to make a fire _________themselves warm. 

—What are you reading these days, Tom?—The book Harry Potter ______ by JK Rowling.

—How do you spend your weekends?—At weekends I prefer _______ at home to _______ out.