Question

高中英语，短文改错，最后一行solve为何加ing

Answer 1

to 是介词，介词后加名词或ing

Answer 2

in the future, i think school life will be different from now. there will be no teachers in the school, and the kids won't go to school, because they will study on computers. not only students but also the teachers won't go to school,either.students will learn fewer subjects. everyone will choose a special subject which they are good at and spend most of their time on it. as for other subjects, they can decide whether to learn it or not. so it also means students will have more free time to do what they want and the school will be smaller because there will be fewer people in it.

Answer 3

the key to doing sth.
固定用法

Answer 4

key是个多义词，用作名词时，是可数名词。主要有如下几种意思：钥匙；答案；关键（要诀）。还有“键盘，音调”等意思。
该词用法的特点是：无论是“钥匙”，“答案”还是“关键（要诀）”，其后一般都是跟介词to，表示对象或目的关系。
Have you got the key to the door? （偶尔也用of）
I don't know the key to the puzzle. 我不知道这个谜语的答案.
Diligence is the key to success. 勤奋是成功的秘诀.
【特别注意】以上例句尽量不要使用介词of，因为of表示“所属关系”，to才表示“目的对象”关系。可以看出，key的上述三种意思与后面名词的关系是后者，因此用to。
Key后用不定式的情况也有，但一般是不定式作定语，或目的状语，不存在“目的对象”的关系。
我查阅了多部英语词典，终于找到了两个例句，跟你的问题一致：
1. Transport has always been the key to developing trade. 运输一直是发展贸易的关键。
2. Modernization is the key to speed up our agricultural development. 现代化是加快农业发展的关键。
这两个例句出自同一部词典。显而易见，句(1)的to是介词，表示“目的对象”关系；句(2)是动词不定式作定语。
　 　

Answer 5

没错，就是用solve