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 lookout 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
423.at large (=at liberty， free)在逃，逍遥法外
at large (= in general) 一般来说，大体上
at large (= at full length; with details) 详细地
424.lean against(背)靠着……
425.at least 至少;at most 至多
