Question

They have made much progress__(用）their hard work.

Answer 1

They have made much progress__(用）their hard work.

这个“用”，是“以....的方法”，with
如：With the help of the computer we can do lots of things.
用了电脑，我们可以做许多事（在电脑的帮助下）

by也可以是“以...”、“通过...”，by doing更常用，with sth.更常用
本句中their hard work是个名词，所以用with比by更好
但如果是asking often and learning，就用by更好

Answer 2

through

Answer 3

with

Answer 4

by