VOA慢速英语:Everyday Grammar - Simple Past and Present Perfect

simple past tense – n. the basic form of the past tense in English. It is used to describe events that finished at a specific time in the past.

present perfect tense – n. A grammatical combination of the present tense and the perfect aspect, used to express a past event that has present consequences.

unspecified – adj. not specified or particular

clarify – v. to make (something) clear or clearer: such as

duration –n. the length of time that something exists or lasts

victim – n. a person who has been attacked, injured, robbed, or killed by someone else

pale – adj. light in color

profound – adj. having or showing great knowledge or understanding