Siempre puede realizar mejor bajo presión
true or false? ?

The answer would be false, becasue it says "better" you would do your best or better work when you're not under pressure.

Hope this helps. 

Choose the correct answer. what does this trip remind charlie of? the walks he took with his family to camp in the desert for one night. the excursion that he made in the fifth grade to the salt mines. the expensive price of salt in supermarkets in his town. the crafts they bought in guatemala.

For this question, it will be important to use the words "mejor" (better), "lo mejor" (the best), and "lo peor" (the worst). while "mejor" is comparative (you are comparing one thing to something else), "lo mejor" and "lo peor" are superlative (there is nothing else better or worse than what these words are describing - there is no comparison).  you could say something like: la música rap es mejor que la música clásica - que es lo peor - pero la música rock es lo mejor de todas las formas de la música (rap music is better than classical music - which is the worst - but rock music is the best out of all the forms of music).