考试经验总结：介词at和in用法
例：Li and I arrived at Heishan county safe and sound， all is well. Don‘t worry. 李和我平安地到达黑山县，一切很好，勿念。
I live in a great city （big city）， my sister lives at a small town while my parents live at a village. 我住在大城市，我姐姐住在一个小城镇，而我的父母则住在农村。
I‘m in Liaoning， at Anshan. 我住在辽宁省鞍山市。
有形with无形by，语言 、单位、材料in
例：The workers are paving a road with stone. 工人们正用石子铺路。（有形）
The teacher is correcting the paper with a new pen. 这位教师正用一支新笔批改论文。（有形）
“Taking Tiger Mountain by Strategy” is a good opera. 《智取威虎山》是-出好戏。（无形）
The product is separated by distilation into gasoline and gas oil. 这种产品是用蒸馏分离出气油和粗柴油。 （表示方式、手段、方法-无形）
I really can‘t express my idea in English freely in-deed. 我确实不能用英语流利地表达我的思想。 （表示某种语言用in）
I wrote a novel in Russian. 我用俄语写了一本小说。（同上）
The kilometer is the biggest unit of length in the metric system. 公里是米制中最长的长度单位。 （表示度、量、衡单位的用in ）
The length is measured in meter， kilometre， and centimetre. 长度是以米、公里、厘米为单位来计算的。（同上）
This board was cast in bronze not in gold. 这个牌匾是铜铸的，不是金铸的。
特征、方面与方式、心情、成语惯用in
特征或状态：
例： The Democratic Party was then in power. 那时民主党执政。
They found the patient in a coma. 他们发现病人处于昏迷状态。
He has not been in good health for some years. 他几年来身体一直不好。
Many who came in despair went away in hope. 许多人带着绝望情绪而来，却满怀希望而去。
The house was in ruins. 这房屋成了废墟。
The poor girl was in tears. 这个贫苦女孩泪流满面。
Her clothes were in rags. 她的衣跟穿破了。
His shoes were in holes. 他的鞋穿出窟窿了。
I only said it in fun. 我说这话只是开玩笑的。
She spoke in grief rather than in anger. 与其说她讲得很气愤，不如说她讲得很伤心。