They can. I don't understand why you think they can't..or why someone has led you to believe you can't. Some of my closest friends have been male...and yes they were just friends, complety platonic relationships. When I was in the hospital many years ago....it was my guy friends that were first to the hospital....at least excluding my family they were the first. As soon as they found out, they came rushing over and made an appearance every day to make sure my family had everything they needed. They even brought me a dozen roses and baseball tickets!! I couldn't have asked for better friends. They are all married now and I don't get to spend as much time with them as I used to...but if they ever need me....they know I'm here.
They absolutely can if you have common interests and respect for eachother. Real friends respect eachother's principles, standpoint and morality. I have a male friend, who happens to be my "best" friend. We've been friends for 11 years and we respect and love eachother to death. It doesn't matter whether a friend is male or female. What matters is the respect you have for yourself and others.
They can't, guys are always after one thing no matter what age they are. My husband admits it! Hope this helps. Guys are not programmed to be "just friends" it's not in their nature.
It may depend on their age. Teens are often so hormonal that even if they want to just be friends it is hard for the boy to turn off that need.
I don't know why some think you can't all my friends were guys growing up.