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 compressor. As it’s pressurized, it …………………… (gets / got / get) hot by absorbing the heat around it. This hot gas then ………………… (passed / passing / passes) through a radiator outside to be cooled by the air outside which is cooler than the compressed gas. The cooled Freon still ………………….. (is remaining / remained / remains) compressed. It is then ………………… (expands / expanded / expanding) into another radiator where it cools off a lot as it expands. When air in your room gets blown across this cold radiator, it ……………….. (become / becomes / has become) cold too. This is also how most refrigerators and freezers work.

Answers

An air-conditioning system uses a refrigerant gas like Freon to cool the air. Freon is placed in a sealed system and is then pressurized using a compressor. As it’s pressurized, it gets hot by absorbing the heat around it. This hot gas then passes through a radiator outside to be cooled by the air outside which is cooler than the compressed gas. The cooled Freon still remains compressed. It is then expanded into another radiator where it cools off a lot as it expands. When air in your room gets blown across this cold radiator, it becomes cold too. This is also how most refrigerators and freezers work.