参考答案

正确答案：B
解析：[听力原文]
When does an engineering student begin to concentrate in a special field?
由选项猜测本题与大学中的某个时间有关，听录音时要注意时间的表达法。本题关键句为“When they are sophomore, an engineering student begins to concentrate in special field.”大二的时候工程师专攻某一领域，故正确答案为B)。