Let's evaluate each sentence for grammatical correctness:
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The sidewalks in the courtyards has been decorated with chalk.
- Incorrect. It should be "have" instead of "has" because "sidewalks" is plural.
- Correct version: "The sidewalks in the courtyards have been decorated with chalk."
-
The surface of the parking lots were redone this summer.
- Incorrect. It should be "was" instead of "were" because "surface" is singular.
- Correct version: "The surface of the parking lots was redone this summer."
-
The bike on the bike rack is blue.
- Correct. This sentence is properly structured.
-
The cars in the parking lot belongs to the teachers.
- Incorrect. It should be "belong" instead of "belongs" because "cars" is plural.
- Correct version: "The cars in the parking lot belong to the teachers."
So, the correct sentence among the options provided is: "The bike on the bike rack is blue."