Hxen.com's tips：Every day persisted can learn English well!-->■Learn English Everyday■
opportunity – n. an amount of time or a situation in which something can be done
bystander – n. a person who is standing near but not taking part in what is happening
cardiac arrest – n. medical temporary or permanent stopping of the heartbeat
compression – n. the act, process, or result of pressing something together or pressing on something
went viral – expression becoming very popular by circulating quickly from person to person, especially through the Internet
