Choose the word or phrase (a, b, c or d) that best fits the blank space in each sentence.

Now the air in our city is________ than it used to be. Something must be done to stop people from polluting it.

Suy nghĩ và trả lời câu hỏi trước khi xem đáp án

ATNETWORK
ADMICRO
YOMEDIA
ZUNIA9