真的！是的！ Really!=真的！是的！ Really？= 是真的吗？

Really! 真的吗!

Just like the "really "in english ,in different situations it has different means,you can translated it into 是吗？真的啊？the big diffrent is the tone you say it. overall,when you believe something but it's a big surprise you use a rising tone and when you don't believe it ,you just think it's a lie,you use a falling tone .

zhende 真的 zhende ma ? 真的吗？

"zhen de ma?" - 'really?' / "zhen de!" - 'really!'. noticed that they differ from the particle "ma" which is used in question. or "shi ma?" - 'is it?' / "shi de!" - 'it is!' :)