⇒ 你去银行吗？ (Nǐ qù yínháng ma?) Are you going to the bank?
(表示反问)
⇒ 你不是去过她的家吗？ (Nǐ bùshì qùguo tā de jiā ma?) Haven't you been to her house before?
吗 (ma) is added to the end of any statement to turn it into a simple yes/no question, e.g.你忙吗？ (Nǐ máng ma?) (Are you busy?), whereas 呢 (ne) is added to the end of a statement to form a tentative question, or to indicate thata response is expected, e.g. 你好吗？我很好，你呢? (Nǐ hǎo ma? Wǒ hěn hǎo, nǐ ne?) (How are you? Fine, and you?).