吗 is usually attached at the end of an affirmative sentence to form an interrogative sentence. We use such questions to get confirmation.

People use 吗 to ask something, it often at the end of declarative sentence. eg: You have eaten.你吃过饭了。 Have you eaten? 你吃过饭了吗？ My English is bad, I wish you will understand it. :)

to make a general question out of a statement

Add 吗 at the back of the sentence when you are asking a question. For example: 你好吗？How are you? 是吗？ Is it？ Add 啦,呀 when you like to emphasize on something. For example: 快点啦/呀！Faster!

At the end of an affirmative sentence, the particle changes the sentence into a question. It's wonderful.