(n.) the speed at which somebody walks, runs, or moves

(a)  

(v.) to perform a particular job or role

(a)  

(n.) information, documents, etc., that show that something is true

(a)  

(adj.) difficult to understand or deal with

(a)  

(n.) a person being used to study something, especially in an experiment

(a)  

(prep.) as stated or reported by someone or something

(a)  

(v. phr) to trust or have confidence in somebody or something

(a)  

(v. phr) to have a meaning that can be understood

(a)  

(adj.) doing something well and with no waste of time, money, or energy

(a)