Our country are working even harder now to _______ the gap between the developed countries and ours.

Traditionally, college students hold a graduation ceremony to encourage themselves when they are to _________ on their life journey.

The room is not bright enough. I need to alight on the ceiling.

The old man lives alone on an island, andhis home is not accessible ______ by boat.

Scientists are working hard to make _______ possible for people to live on Mars in the future.