Those who have __________ floods and sandstorms knows the importance of environmental protection.
It is said that this is the biggest lab ________ they have ever built in their school.
In order to attract more customers, many supermarkets usually sell their goods at a good________ at weekends.
It will be at least three weeks________ he recovers from his illness and returns to work.
He found his house broken into and many things stolen _______ his return from office.
Making good friends is no ________ important to us than choosing a good job; we should take both of them seriously.