导读：词组能有效的帮助大家提高完型和句子的理解与写作质量，为保证大家能够灵活运用考研重点词组，社科赛斯李梅老师特配以相应的例句，帮助大家更快地获得更高的分数。
611. on (one's) guard 警惕，提防；站岗，值班
We must be on (our) guard against hidden enemies.
我们必须警惕暗藏的敌人。
612. on (the) one hand 一方面
On one hand, I'm inheriting a new son-in-law.
一方面，我现在有了一个女婿。
613. on (the/an) average 按平均值，通常
American shares rose, on (the/an) average, by 38%.
美国股票价格平均上涨了38%。
614. on a large/small scale 大/小规模地
This movement has aroused the masses on a large scale.
这次运动，群众发动的面很广。
He's in business on a small scale.
他做的是小本生意。
615. on account of 由于
The flight was postponed on account of bad weather.
因为天气恶劣，飞行延期了。
616. on behalf of 代表
He spoke on behalf of all the members of the faculty and staff.
他代表全体教职员工讲了话。
617. on board 在船(车/飞机)上
My wife and I were the first to arrive and hopped on board.
我和妻子是最早赶到登船/上车/飞机的。
618. on business 因公
I presume you're here on business.
我想你是来这里出差的。
619. on condition that 如果
You can use the bicycle on condition that you return it tomorrow.
只要你明天归还，自行车你可以拿去用。
620.on duty 上班，值班
We'll take our turn on duty at 1 p.m.
我们下午一点接班。
