Choose between because and because of in the sentences below. Because / Because of his poor editing, he failed the assignment. Their presentation was very well prepared because / because of their excellent group work. The students couldn’t complete their work because / because of the internet was down. Because / Because of the amount of information on the internet, we can find out about anything. Are you having problems because / because of you don’t understand the lesson? The students enjoyed doing the quiz, because / because of the questions were very easy.