Looking at his arm in a cast

[Bassim]

I am wondering if my sentences are grammatically correct.

Looking at his arm in a cast, Peter pondered about how stupid he must have been when he rode his motorcycle while drunk. He could have been dead, and all that happened because of a few pints he had in a pub.

 

[J&K Tutoring]

It is grammatically correct, but it could be better.

1. "... pondered about..." To ponder is to think about something, so "pondered about" = thought about about.
2. "He could have been dead" Being dead is not a thing one can 'be' in the past and then 'stop being' in the past. Once you're dead, you're dead. 'He could be dead' OR (better) 'He could have been killed'.
3. "... all that happened..." All what happened? The only thing that "happened" is he broke his arm.

 

[Bassim]

I will repeat my sentence after J&K Tutoring's corrections.

Looking at his arm in a cast, Peter thought about how stupid he must have been when he rode his motorcycle while drunk. He could have been killed, and all this trouble because of a few pints he had in a pub.