题目内容：

In order to be successful as an engineer ,she had to become ___at mathematics.
A.proficient B.outstanding C.prominent
D.experienced

优质解答

proficient 熟练的,精通的 常用be proficient at/in doing
outstanding 突出的,显著的
prominent 突起的,显眼的,著名的
experienced 有经验的
所以选A