Fill in the blanks (1), (2) and (3): Pollution is a (1)_____ problem in big cities. Factories (2)_____ smoke into the air, and vehicles (3)_____ harmful gases.

Question

Accepted Answer

serious / release / emit. Adjective before 'problem'; plural subjects take plural verbs

Fill in the blanks (1), (2) and (3): Pollution is a (1)___ problem in big cities. Factories (2)_ smoke into the air, and vehicles (3)___ harmful gases.

Explanation