題目：
1.Betty's grade is good.
2.Ben's grade is very good.
(以Betty's grade為句首，用比較級合併句子)
擬答如下3種是否都可以？哪句最好？
1.Betty's grade is less good than Ben's.
2.Betty's grade is worse than Ben's.
3.Betty's grade is not better than Ben's.

Betty's grade is not as good as Ben's.