Everyone must __________ the security check (安检) before getting on the plane at the airport.— Yes. It’s necessary to ensure the passengers’ safety.

” ______ do you write to your parents?” “Once a month.” [ ]

Do you know the song Gangnam Style? —Of course. It interesting.

John and Peter like to __________ their life.

I shall never forget those years ______ I lived in the country with the farmers, ______ has a great effect on my life.