你怎么做？
nǐ zěnme zuò?
How will you do it?
这东西怎么用？
zhè dōngxi zěnme yòng?
How do you use this?
你怎么不来？
nǐ zěnme bù lái?
Why didn't you come?
他怎么这么晚？
tā zěnme zhème wǎn?
How come he's so late?
