50. Drop Out
drop out ： to withdraw from 退出。
如：He has decided to drop out of politics .
他已经决定退出政坛。
Seven students dropped out of university last year .
去年有七个学生从大学里退了学。
51. This is one of the oldest expedient ， ……=expedient ： a temporary means to an end 权宜之计
如：resort to an expedient 采取权宜之计