I have several issues with this one. 1) "～십시오" is a very polite ending, so it strongly implies "please + verb" in English. 2) "Clean up" is more accurate and natural. Cleaning is in general, cleaning up is to complete a specific task. 3) Finally, "leaves" should be accepted for 낙엽. If you are cleaning them up, OF COURSE they are on the ground, they are fallen. Saying fallen leaves is redundant and we native speakers absolutely don't say "fallen". We're not going to clean up the leaves that are still on the trees. Hopefully, this answer will get "fixed up" soon!!