can prepositions come at the end of the sentence

Answer 1

No.

Prepositions always have to begin a phrase that ends with a noun or pronoun.

The confusing thing is that some prepositions may be used as adverbs and can end a sentence.

Examples:

Preposition: This book is about a courageous boy.

Adverb: The papers were strewn about.

Answer 2

http://news.bbc.co.uk/1/hi/magazine/7595509.stm

Read Mr. Graves' comments (number 19)

Answer 3

Bobpursley has just given you an example of the word, "up" that can be used as either a preposition or an adverb. In his example, "up" is used as an adverb.

The site he posted is right. In casual speech it's o.k. to ask, "Who are you going with?" However in formal writing, avoid ending a sentence with a preposition. Reword the sentence so that you don't commit this error.