问题补充：
John plays the piano , if not better than, David. But he never shows off in public.
A. as well
B. as well as
C. so well
D. so well as
答案：
A. as well
(答案→)B. as well as
C. so well
D. so well as
解析：这是一个比较状语从句，引导比较状语从句的连词和词组有：as…as,
than, not so…as, the more…, the more…等。这是个肯定句，所以不能用D，因为有比较的对象也就是有宾语，所以不能省略第二个as.
