______ 2010 Shanghai World Expo is a perfect opportunity to get ______ panoramic (全景的) view of the whole world without traveling thousands of miles.
Experts have been warning _____ of the health risks caused by passive smoking.
He was told that it would be at least three months ___ he could recover and return to work.
Scientists are convinced ___ the positive effect of laughter ___ physical and mental health.
We had to wait half an hour _______ we already booked a table.
Help others whenever you can ______ you will make the world a nicer place to live in.