Một tia sáng đi từ nước đến mặt phân cách với không khí. Biết chiết suất của

It’s compulsory for people to check their passports before entering the port.

He’s a respected athlete; he’s won the world tennis championship for the third successful year.

Electric bikes are becoming increasingly popular nowadays thanks to its convenience.

Mary helps her grandmother to grow some kinds of vegetables last weekend.

Stockholm dwellers are fortunate to live in one of the greenest capitals in the world.

The athlete’s bitter defeat in the match dealt a blow to his hopes of defending his title at the championship.

I think it’s impossible to abolish school examinations. They are necessary to evaluate students’progress.