用英语说:"如果你还没有男朋友,我想做你的男朋友"

朋友，你是不是没学过英语呀。我帮你吧。If you don't have a boyfriend,I want to be your boyfriend.

If you have not got any boyfriend, I would like to be the one.
If you have not got any boyfriend, I would like to be your boyfriend.

If you have no boyfriend, I'd like to be!

Recommended translation from British MSc student:
I'd like to be your boyfriend if you haven't got one / if you don't have one.

"No boyfriend yet? let me be the one."