1. In the sentence 你们应该知道我们第四级的课程快要结束了, the 快 is used to show an action that is about to take place (in this case, level 4 is about to finish).

Similarly, you might hear someone say 我们快到了.

2. Note the use of 越来越 in 最近，世界上有很多城市的经济发展越来越快, 也越来越好. In English, the word “expanding” already has the meaning of “more and more” built into it. However here, the “more and more” emphasis is placed on the “quickly” and “well” words.

3. Note how in addition to simply using 如果, we can also use 的话.

a. 如果你的公寓变得很乱的话…
b. 有这样的问题的话…