[ Grammar ]
An air-conditioning system _______ a refrigerated gas like Freon to cool the air
A. Using
B. Use
C. Uses
D. Used

Random Topics:
Wish SentenceTo Infinitive/Bare Infinitive/GerundsTenses & PassiveBasic Grammar-ed and -ing AdjectivesPast Tense & Present Perfect TenseVerb and PrepositionAdjective SuffixesHave to / Do not have toPast Simple and Past ProgressiveOther quiz:
Future Perfect Continuous › ViewYou ______ money for 50 years.
A. will be saving
B. will have been saving
C. will have being saving
D. will have saving
Tenses › View
How ______ now? Better than before?
A. you are feeling
B. do you feel
C. are you feeling
Type of Sentences › ViewDon’t slam the door!
A. Imperative
B. Interrogative
C. Declarative
D. Exclamatory
Understanding Product Packaging and Tenses › View
What is the main purpose of a procedure text?
A. To explain a process
B. To persuade
C. To inform
D. To entertain
