This is____ a difficult problem ____ all of us can't work it out.
Was it in 2002 __________ he was still at middle school __________ the boy became expert at computer?
The professor wants the students to pay more attention to the festivals ______ in other parts of the world.
The news has spread all over the country ________ an earthquake happened last night.
It’s too late. Go to bed right away. Forget you need to get up as early as you can ______ the early train?
Lucy works hard as usual and it has_________. She got the first in the English Speaking Contest.