When a valve is closed, it seals against a machined area in the cylinder head called the?
a. valve guide
b. head gasket
c. valve seat
d. cylinder head port

Which of the following statements about revision is most accurate? (a) you must compose first drafts quickly (sprint writing) and return later for editing. (b) careful writers always revise as they write. (c) revision is required for only long and complex business documents. (d) some business writers prefer to compose first drafts quickly and revise later; others prefer to revise as they go.

(a) what was the opportunity cost of non-gm food for many buyers before 2008? (b) why did they prefer the alternative? (c) what was the opportunity cost in 2008? (d) why did it change?

In terms of the "great wheel of science", statistics are central to the research process (a) only between the hypothesis phase and the observation phase (b) only between the observation phase and the empirical generalization phase (c) only between the theory phase and the hypothesis phase (d) only between the empirical generalization phase and the theory phase