1, a, I bought this hat for my sister in Nha Trang.
⇒ Who did you buy this hat for in Nha Trang?
b, I bought this hat for my sister in Nha Trang.
⇒ What did you buy for your sister in Nha Trang?
2. Nam often goes to school by bike.
⇒ How does Nam often go to school?
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