根据句意，用所给动词的适当形式填空。
When I saw the parade in Disneyland, I couldn’t stop ___________ (take) photos .
It takes about three hours ___________ ( fly )to Hong Kong .
Students should read more books ___________ ( improve ) their writing .
Sadly, the little dog ___________ (die) for some time .
You must ___________ (return) these books to the library as soon as possible.