历年考研英语常考词语的固定搭配by accident 偶然例句：Columbus discoverde America by accident. 哥伦布偶然发现了美洲。on account of 因为，由于例句：Illness caught him inevitably on account of overwork. 由于工作过度，他生病是不可避免的。in addition 另外 例句：In addition to an album, I gave him a pen and a pencil.除了一本照相簿外, 我还给了他一支钢笔和一支铅笔。in the air 在流行中，在传播中 例句：We can see many molecules flying in the air when a sunbeam penetrated the dark room.当一束光线穿进暗淡的房间时，我们可以看到空气中有许多小颗粒在飞舞。on (the/an) average 平均，一般来说例句：On average w
