Answers: "You yourself should try to understand the lesson." and "Before running the marathon, Tom himself ate three plates of pasta."
Explanation: Intensive pronouns are often used to add emphasis to the subject of the sentence, so the answers would be the two sentences above. The reflexive pronouns include myself, yourself, himself, herself, themselves, etc.
The earth's crust is the outermost layer of the planet. it is very thin and is just like the skin of an apple. the crust is about 3-5 miles thick and about 25 miles thick under the continents.
This is interesting. It's a split between C and D for this, as it covers both almost equally. However, I would go with C, seeing as it all falls under the umbrella of "cultural significance", even when talking about what purpose the drum is being changed for.
