—You look so worried, what’s wrong?—More and more people like me become to worry about the __________ pollution  after the haze (雾霾) appeared in Beijing and some other cities in China.

—What’s your favorite color?---My favorite color is________.

---Oh, my God! We have missed the last bus. What shall we do?---I’m afraid we have no ________ but to take a taxi.

The dolphins are ______ interesting in the zoo.

There are three __in the office.