How do we know if a sentence is in the active or passive voice?
In an active sentence the subject is the agent. It does the action to something else, the object.
In a passive sentence the subject receives the action. The agent may or may not be included in the sentence.
500
will have kicked
Future Perfect
500
Can you know which part of speech a word is just by looking at it?
No, you have to see it in a sentence.
500
Style wise, when is it good to use active voice, and when is it good to use passive voice?