X. Rewrite the following sentences, using the provided word keep meaning as that of the root one.

33. I've never had to wait this long for a bus before.

=> This is……………………………………………

34. Remember to take note of what the tour guide said.

=> Remember to put……………………………………

35. It took us more than 3 hours to discover the inner Hanoi.

=> We spent……………………………………………

36. No other book is more popular than Dickens' "David Copperfield".

=> Dickens' "David Copperfield" is …………………………………