4.In each of the following groups of words, there are four underlined letters or letter combinations marked A, B, C and D. Compare the underlined parts and identify the one that is different from the others in pronunciation.
A、cool
B、flood
C、food
D、moon
Your brother Frank doesn't eat cheese, ____?
A、is he
B、isn't he
C、does he
D、doesn't he
We generally have four people working in the shop, but at ____ periods we employ extra hands.