How to use "preserve" and "protect"?

How to memorize tons of words and fully understand them in a short time? How can I memorize a lot of words in a short time?Thanks.

How to memorize tons of words in a short time?

Is it important to focus on the differences among some words that have similar meanings? I am always confused about the differences among some words that have similar meanings such as "impotent,unable and incapable." Should I focus on them?If so,how can I get the differences quickly and easily? Thank you!

the differences among "be puzzled at","be puzzled about" and "be puzzled with"