If you could give us any example sentence with ‘Can we’…?, we’d be able to answer you more easily. I suppose you will use ‘Can we…?’ in several ways, and we might use different wording for each.: “Can we eat this?” as: 1) May we eat this? / Are we allowed to eat this? = これを食べていいですか。 2) Can people eat this? / Is it possible to eat?/ Is this edible? 　　　　　　= これは食べられますか。 “Can we start now(, couldn’t we)?” as: 3) Let’s start! 　　　　　　= はじめましょう。(polite form) / はじめよう。(plane form) And, though it sounds curious, “Can we eat this?” as 4) Are we able to eat this? 　　　　　　= 私たちはこれを食べるられる(だろう)か？ 　　　　　　　　私たちはこれをたべることができる(だろう)か？ Hope this will help you a bit, and if there is no fitting sentence to tell what you’d intend, please tell so with an example sentence.

Kevin, thank you so much for the very detailed and useful response with links! Yes, I try to remember that Japanese is not spoken in the same way as English which is why I asked if "Can we" is a common expression, but I'm a work in progress and still very much learning what expressions are used in both languages and which are not. I'll keep at it! Thanks again :)

Also check out Orsinia's excellent answer. I definitely see the 〜いいですか expression a lot and it literally translates to 'is it good?' That's not a common way to speak in English, but it is a very common expression in Japanese. Which means, rather than asking how would I literally translate my English, you should learn about how do Japanese people commonly express themselves.

There is a principle, but it is not 100%. Check out the discussion here: http://forum.jisho.org/discussion/231/difference-between-a-%E3%82%8B-verb-and-a-%E3%81%86-verb/p1 I think it's much better to worry less about the principles and carry on with learning the most common verbs and learn how they can be used differently as you study more grammars. Then use those verbs in those different forms. There is a website that can help you as a reference http://www.japaneseverbconjugator.com. But once you are well-versed in the common verbs, you can then use that as a guide to guess unfamiliar verbs in the future while maintaining to reference it in case you're in error. I know this bit can be quite frustrating because there is no absolute principle that makes learning easy, but do hang on :)

Thanks Kevin, so how do I know which verbs get which ending?