There is no denying the fact that as one grows older，one’s memory ______.[ ]

__ to look after luggage for someone else, inform the police at once.

In my opinion , the thief is likely to come, please look _____ for him .

, Chinese people celebrate the Mid-Autumn Festival by enjoying the full moon and eating mooncakes.

The professor’s research finally proved to be ______, though he had spent a lot of money on it.