vi.　走得极慢；落后go too slowly;not keep up with

　～ far behind　远远落在后面
　～ behind　落在…后面
　～ far behind other countries　远远落后于其他国家
　～ in　在…方面落后

　The child lagged because he was tired.　那孩子因累了而走得很慢。
　Ten minutes later, some of runners in the race began to lag.　十分钟后，有些参赛的人开始落后了。

 ♣ lag behind¹　(v.+adv.)
1. 落后fall behind
　The lame child lagged behind.　那个跛脚的小孩落在后面了。
　Why is this country lagging behind in the development of space technology?　这个国家为什么在航天技术的发展方面落后了?
2. 逾期付款be late, as with the payment of money
　If your payments of rent lag behind, you will be asked to leave.　如果你不如期交房租，你就会被赶走。
 ♣ lag behind²　(v.+prep.)
1. 行动上慢于be slower than sb/sth
　Why does she always lag behind others when we're out for a walk?　为什么外出散步时，她总落在后面?
2. 落后于fail to remain level with sb/sth
　Britain's economic development must lag behind that of almost every other industrial nation.　英国的经济发展肯定落后于几乎所有的其他工业国。

 ♣ lag, dawdle, delay, loiter, procrastinate
　参见delay条。

C 滞后，（时间上的）间隔delay;period of time separating two events

　cause a ～　延误
　cultural ～　文化落后
　noticeable ～　显而易见的落后
　jet ～　跨时区高速飞行后，生理节奏的破坏
　time ～　时差
　without ～　毫不迟延地
　～ between composition and publication　排版和出版之间的相隔时间

　This work must go forward without lag.　这项工作必须毫不迟延地进行。
　There is a time lag of about fifteen years.　时间上有一段约15年的间隔。

　［同义词］ v. delay, drag, halt, hang back, limp n. delay, drag, setback, slowdown
　［反义词］ v. go ahead, hurry along, lead n. advance, speeding up
　［词源］中古荷兰语lakke（缓慢行走）