It's 20 minutes from the city to the center by underground .
( 楼主打错了一个单词吧?有一个FROM 应该是to ,因为from ……TO 从……到……）
加油!不明白再问!没错，题目是这样的在回答一下那就是题目出错了。饿要不就是把away 打成from即：It's 20 minutes away from the city center by underground .