大学英语：重要词汇invest in 投资

412.be involved in(=become connected or concerned)卷入，参加

413.by itself(=alone，without help)单独地，靠自己

414.in itself 本身;of itself 自发，自然

415.be jealous of 妒忌

416.jump at(=to be eager to accept)抢着接受

417.jump on(=scold，tell of)叱责

418.junior to sb. 年纪较…轻，职位较…低.

419.(be)keen on 喜爱，渴望

420.keep a close watch on(=keep a sharp look out for)密切注视

421.keep…to oneself(=keep secret)不告诉别人

422.to(the best of)one's knowledge 据…所知