3-13. use, uses, to use, using, used.
[You use this thing.] = You do something with this thing because you think this can cause something to happen that you want.
[I used something big to cause people far from here to see me.]
3-14. each, each of.
[You know X about each of these things.] = There are two or more things. You think about all these things like this: If something is one of these things, then you know X about it.
[Each person here said something to me.]
3-15. exist, exists, to exist, existing, existed.
[Someplace an X exists.] = Someplace there is an X, or someplace an X is alive.
[This kind of thing did not exist before this time.]
3-16. become, becomes, to become, becoming, became.
[J became K.] = Something happened to J for some time. After this happened, K is something true you can know about J. But before this happened, K was not true.
[These two animals were small before, but they became big.]
There are some animals here.
Each of these animals was small when it existed a short time.
After a long time, each of these animals __________.