大学英语： crack n. 裂缝

She found a crack in one of the tea-cups.〔她发现一只茶杯上有裂缝。〕

He heard the cracks of rifle fire in the distance.〔他听到了远处的步枪声。〕

He asked his mother to crack some eggs for him.〔他请妈妈帮他敲碎几个鸡蛋。〕

His face cracked with a broad smile. 〔他咧开嘴笑了。〕

The phone cracked the room's quiet.〔电话铃声打破了房间的寂静。〕

They were unable to crack a highly competitive sales market.〔他们无法打进竞争激烈的销售市场。〕

8. crust n. 地壳;面包皮，外皮

There are some brownish bread crusts on the dining table.〔餐桌上有一些棕色的面包皮。〕

The white snow had a fine crust on the trees.〔树上覆盖着一层美丽的白雪。〕

The continuous movements of the earth's crust may lead to earthquakes.〔地壳的不断运动引发了地震。〕

It is very dangerous to walk on the thin crust of ice.〔在这样一层薄冰上行走是很危险的。〕