问题补充：
Sensible people don’t think it is to buy things which are not needed even at a low price.
A. worth
B. worthy
C. worthless
D. worthwhile
答案：
A. worth
B. worthy
C. worthless
(答案→)D. worthwhile
解析：It is worthwhile to do sth“值得做某事”。
it is worth doing sth
it is worthy to be done
It is worthy of being done
