问题补充：
Swimming is diving.
A. more dangerous as
B. not as dangerous as
C. not as more dangerous as
D. not more dangerous as
答案：
A. more dangerous as
(答案→)B. not as dangerous as
C. not as more dangerous as
D. not more dangerous as
解析：句意：游泳不如潜水危险。分析：as……as与……一样；而not as(so)…….as不如…….。中间接形容词或者副词的原级。分析选项只有第二项符合题意。故选 B
