real/really

[Allifathima]

1. This film is based on real life.
1a. This film is based on a real life.
2. The really hot weather affected everybody.
2a. The real hot weather affected everybody.
Are all these sentences grammatically OK?
Please compare the meanings of #1 & 1a and also #2 & #2a?

[Beeesneees]

The meanings of 1 and 1a vary:
1. the film is based on real life events;
1a. the film is based on somebody's life story.

2a is incorrect.
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Cheers m' dears!

[Bwriter]

This is REALLY interesting :)