Answer:
1- Fast
2- Hot
3- Empty
4- Expensive
5- Lazy
6- Cold
7- Happy
8- Slim
9- Slow
10- Dirty
11- Poor
12- Old
13- Heavy
14- Clean
15- Dry
16- Young
17- Fat
18- Wet
19- Light
20- Difficult
21- Easy
The secret message is To teach is to learn twice .
I hope I helped you^_^
