Class 9 Verbs Gap Filling Worksheet
Fill in the blanks with an appropriate verb form. Class 9 gap filling exercise An air-conditioning system ………………… (use / using / uses) a refrigerant gas like Freon to cool the air. Freon …………….. (places / is placed / placed) in a sealed system and is then ………………… (pressurizing / pressurizes / pressurized) using a …