根据句意，用括号内所给单词的适当形式填空。
Look at ____________ (you) in the mirror. How dirty your faces are!   
It’s surely the __________ (tough) experience in his life that the brave young man has had. 
Seven ____________ (twelve) of the students in our school are boys. 
All of them want to know how the matter is ____________ (progress) at the moment.