题目内容：

This is ( )as the one you bought yesterday
A.such a good pen
B.as a good pen
C.so a good pen
D.as good a pen
麻烦说明下选择的理由,

优质解答

B.as a good pen
This is as a good pen as the one you bought yesterday
这个笔跟你昨天买的一样好.
D.as good a pen是错的,因为a应该加在good的前面,因为good是形容这只笔所以也算笔的一部分.