It depends what you mean by "to clean," since in English that can be used for several things. For example, if you're cleaning the house, that's 청소(를) 하다. If you're cleaning the table, they use 닦다 (literally, "to wipe"). If you're cleaning some other object by washing it, they use 씻다 ("to wash").
Hi!
For the example " 일주일 뒤에 시험이 있어요" we can also say "다음주에 시험이 있어요"? Is it right?
Yes, you can change the time to whenever you'd like 🙂
How does one say the action verb "to clean", not the descriptive verb or adjective "to be clean" which is in the pdf example?
It depends what you mean by "to clean," since in English that can be used for several things. For example, if you're cleaning the house, that's 청소(를) 하다. If you're cleaning the table, they use 닦다 (literally, "to wipe"). If you're cleaning some other object by washing it, they use 씻다 ("to wash").