We generally have four people working in the shop, but at ____ periods we employ extra hands.
A、top
B、rush
C、tip
D、peak
The old man's clothes, ____ old and worn, looked clean and of good quality.
A、if
B、when
C、though
D、since
3.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.