Midterm Review Corrections:

1)
One of the students at the review session emailed us about "butfirst" and "butlast". If we said in the review session that "butfirst" and "butlast"
will always return a sentence, we misspoke!

"butfirst" and "butlast" will always return a sentence when they are given a sentence. That is, (butfirst '(hello jimmy)) will return the sentence  
'(jimmy), not the word 'jimmy. Likewise, (butlast '(hello jimmy)) will   
return the sentence '(hello) not the word 'hello.

However, given a word, "butfirst" and "butlast" will return a word.
(butfirst 'hello) returns the word 'ello.

2)
We said (or at least implied) that appearances takes the same kind of arguments as member? In fact, 2 “word” arguments is NOT an error in apperances, unlike member?

(member? 'a 'alphabet) ==> #t
(member? 'alpha 'alphabet) ==> error
(appearances 'a 'alphabet) ==> 2
(appearances 'alpha 'alphabet) ==> 0