在职研究生英语（二）
阅读短文，选出填入空格最合适的一项： Online courses have m…
第 2 题单选题模拟题基础
阅读短文，选出填入空格最合适的一项：
Online courses have made it possible for millions of adults to study without leaving their jobs. ___, many learners never finish the courses they start. Without a teacher watching over them or classmates to study with, they find it hard to stay motivated, especially when work gets busy. Course providers are now trying to solve this problem by adding live discussions and weekly deadlines.
完形填空上下文线索解题步骤