1. Sound/ Voice: When someone is speaking, like "Hi!" "Can you hear my VOICE" if you say "can you hear my sound", is wrong, so Voice is describing people's not and object.
Sound: for example, the water is running, and you will say"What's that sound, is it the water?" Sound describes an object that is not alive, is a thing!
2. In/ Inside: There is a big difference, In is when you are in something, for example....
"My socks is in the drawer" is something that is in... Inside, when you want something to enter something, for example.... "Can you go inside and see if Emily is there?"
So don't mistake the two terms!^^
3. Out/ outside: this is the same thing as above, is just different word, for example.....
"I am getting out of this place, it stinks!" for outside....."I want to go outside and ride my bike"
4. Ground/ Floor: if you look it up in the dictionary it gives you the same definition, but it is used differently, for ground....." My ball droped on the ground" Normally is describing outside. If you are in door or just in general, "Don't sleep on the floor, is too dirty!"
So do you understand now, I hope so, I tried and challenge my best ability to help you, if you still don't understand, you can E-mail me.... firstname.lastname@example.org ^^"