It was not until 1911, _______ the first vitamin was identified, _______ people realized the importance of it.
When the plane ____, all the passengers on board should turn off their mobile phones.
--- Do you regret paying ten dollars for the book?---No.I would rather pay ___ that price.
--- The film will begin at seven o’clock.We’ll meet at half past six.Is that OK?---_____.I’ll pick you up at half past six in your home.
-–I’d like to buy a new mobile phone.Mine isn’t popular.---You’d better not since the mobile phones_____ so rapidly.
At first the man refused to answer the questions ____ by the police, but later he had to admit ____the car.