问题补充：
The boy is my sister, so he sits in front of her.
A. as tall as
B. taller than
C. not as tall as
D. the tallest
答案：
A. as tall as
B. taller than
(答案→)C. not as tall as
D. the tallest
解析：本题的含义是那个男孩没有我妹妹高，所以他坐在她前面。not as或so……as……表示……不及……的意思，比较级中表示一样可用as……as，故本题选C。
