Personal letters are letters<span> you write to someone you know. For example, you might write to a friend, family member, classmate.</span>
No improvement to this sentence is necessary. It makes perfect sense on its own and sounds right. "Either" always takes an "or" else the word wouldn't make sense, as it's meant to contrast binary options.
eg.
I'm either going to eat food or drink water.
Conclusion summarizes the main point i think
If we are going to unscramble the given set of letters above, the word that would be formed is "BATHYMETER". So a bathymeter is a device <span>used to measure the depth of water in oceans, seas, or lakes. Hope this answers your question. Have a great day!</span>