The world is changing rapidly and sometimes we find it almost impossible to ________ the advances in science and technology.

The square box has a door,there are some buttons.

Have you ever visited the 2010 Shanghai World Expo? —–Yes．When I was in China , I ______ it twice

The US government threatened that it would ________ all its investment(投资) from the country if the country didn’t reduce the customs duties.

Our teacher often tells us enough sleep every day.