A man kneeling before a machine .
The man kneeled to fix the machine .
A man kneeling before a machine.
The man kneeled to fix the machine.
The an is kneeling by a machine but we cannot tell if he is just looking at  it or kneeled to fix it.
The an is kneeling by a machine but we can not tell if he is just looking at it or kneeled to fix it .