with a relative pronoun: In the past, people had to take a ferryboat to Chongming Island, but now they can drive to it, ______is a great saving of time.
with a relative pronoun: In the past, people had to take a ferryboat to Chongming Island, but now they can drive to it, ______is a great saving of time. 【正确答案】：which 【题目解析】：考察非限制性定语从句，从句部分修饰drive to it ，关系代词用which来指代
