Add punctuation: If your principal customers are other companies you can start with the question of whether it is the customers or you yourselves that determine the products design and function
A: If your principal customers are other companies, you can start with the question of whether it is the customers or you yourselves that determine the product's design and function.

Add punctuation: SND is a kind of sound file developed by Apple Corp SND is supported by Macintosh platform and a variety of Mac applications
A: SND is a kind of sound file developed by Apple Corp. SND is supported by Macintosh platform and a variety of Mac applications.

Add punctuation: If the dog has any indwelling catheters these must be removed
A:
If the dog has any indwelling catheters, these must be removed.