We use 嗎 to make yes-no questions
你好吗？ (nǐ hǎo ma)
How are you?  
我很好。你呢？(wǒ hěn hǎo , nǐ ne )
I am fine, and you?  
我也是，谢谢。(wǒ yě shì , xiè xiè )
Me too, thanks    
你是小华吗? (nǐ shì xiǎo huá ma)
Are you Xiaohua?

你最近好吗？ (nǐ zuì jìn hǎo ma )
How are you doing?  
不太好，你呢？ (bù tài hǎo , nǐ ne)
Not so good, and you?  
我很好，你怎么了？
(wǒ hěn hǎo , nǐ zěn me le)
I am fine. What happened to you?

• We use 不 to express negation. It’s always before a verb.
• 我不是小华 (wǒ bù shì xiǎo huá )
  He is not Xiaohua  
• 你不是阿明 (nǐ bù shì ā míng)
  You aren’t Aming . 
• 他不是美丽 (tā bù shì měi lì)
  He isn’t Meili.

We don’t use 是 “to be” in the sentence like “to be adj./adv”    
你是好吗? How are you?  
我是很好 I am (very) good.  
我不是好 I am not good/ well.
but 我不是很好 I am not very good/ well.