Tìm lỗi sai và sửa lại, giải thích 

Because of the flood happened, many families lost their houses.

He had not idea how difficult the job was.         

Scientists have identified a link between an healthy diet and diseases. 

If there are too many billboards and advertising banners on the street, people may have to deal _______pollution.

 A.with air B.for visual C. with visual D. for air 

The scientists / racing/ find/ best drugs/ treat/  COVID -19.

A.   The scientists are racing to find best drugs to treat COVID -19.

B.    The scientists are racing finding the best drugs to treat COVID -19.

C.    The scientists are raced to find the best drugs to treat COVID -19.

D.   The scientists are being raced to find the best drugs to treat COVID -19.