The teens took a photo of smiling faces to welcome World Smile Day in . (五月)
The (人口) of China is about 1.41 billion in 2021.
Many people think computers and the Internet will (取代) books.
They'd like to go sightseeing (而不是) of staying at the hotel.
Chinese scientists (发送) a spaceship to the planet Mars to take photos in July 2020.
There is nothing (奇怪的) in the box.