Задание

Fans are used to circulate air in rooms and buildings and for cooling and drying people, materials, or products. Even though air that is circulated be a fan is comforting, no fan actually cools the air. Air conditioners use a complicated process to cool the air and create changes in temperature. While repairing a fan is relatively simple, a professional repairman will often have to intervene when home owners face problems with their air conditioning units.

The word to intervene in the passage is closest in meaning to

to get involved

to be interested in

to learn about

to be prepared