Basically, Chinese meaning is also related to the tone you use in your speech. eg. if the tone is rising, it should be a question, if the tone is falling, it can be statement or complaining or conjecture. For the above ending syllables, my view is: 啦 can be question or statement, which depends on the tone (rising is question, falling is statement)n eg. 看见啦？（see?）好啦！（OK） 呢 is usually the ending of question. eg. 你呢？（and you?） 啊 is usually the ending of interjectional sentence. eg.真快啊！（it's so fast!） 吧 is usually the ending of conjecture. eg. 你是Mary吧，对吗？（You're Mary, aren't you?） 哦 usually means "I understand", especially in the MSN or QQ chatting, people can say 哦 means "I understand" just like "Oh" in English.

Actually,your question also confuses many Chinese people. People from different parts of China may have different tones,some are used to lift their tone while others do the converse way.Generally speaking ,“呢”and “吗”are usually used in the end of a question and followed by “?”。The two words show the doubt about something."啊""吧",these two words are interjections,but "啊 will show somebody is more pleased with something or somebody than"吧"。"哦"just mean "I konw it",it is the reply of a question.And I think if you speak Chinese a lot ,you will soon get it.

making chinese sentences,you must pay more attention to the tone (rising is a question, falling is a statement ) as you have known 吗 means an obvious question. 呢 is used like 吗 for example:你的意见呢=说说你的意见好吗？ 啊,哦and 啦 just stands for having known something.for example;我知道啦=我知道啊=哦，我知道啦（besides means peevish） 吧means unwilling to do something .for example 好吧，听听就听听啦

It has been all explained above, I would just add one important detail to 啦 - it's a fusion of 了 and 啊, it combines the meaning of both of them...

啦sometimes is the same with 了,means sth is past ~我吃过啦=我吃过了~ 啊imply sth is plaintful，or exclamation,sometimes means oh~多好的地方啊!What a place! 哦means i see when u only use"哦"to answer sth.If u use is at the end of a sentence,it doesnt mean anything~