The old man's clothes, ____ old and worn, looked clean and of good quality.
A、if
B、when
C、though
D、since
The writer's first book is____ popular than his second one.
A、so
B、less
C、such
D、much
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.