倒下：指因失去平衡或突然倒下。
倒塌：指建筑物或物体因失去支撑而倒塌。
摔倒：指因失去平衡或滑倒而摔倒。
fall over // [ falling fell fallen falls ]
动词词组 If a person or object that is standing falls over, they accidentally move from their upright position so that they are then lying on the ground or on the surface supporting them. 倒下
If he drinks more than two glasses of wine he falls over.
如果他喝酒超过两杯就会倒下。
fall forward and down
同义词： go over
落在
fall over 绊了一跤; 倒下，跌倒; 跌倒,摔倒; 跌倒、倒下; 跌跤; 翻上; 落在; 摔入; 下倾; 向前摔倒；跌倒；倒下..
... fall down跌倒；失败；倒塌 不及物 fall over跌倒，摔倒；绊了一跤 及物与不及物 fall off减少；跌落；下降；离开；衰退 ...
之外; 向前摔倒; 叛向另一方面; [苏]睡着, 入睡 fall over each other [美]争夺; 竞争; 争先恐后; 你争我夺 ..
When the babies see the keepers, they run over with excitement and some of them even walk into their friends and fall over!
当宝宝们看到饲养员时，它们兴奋地跑过来，其中一些甚至撞到它们的朋友们，摔倒了！
Their legs lock in place so they don't fall over.
它们的腿固定在原地，这样它们就不会摔倒。
Keep an eye on your younger brother. It is easy to fall over when babies learn to walk.
注意你弟弟，小孩子学走路时容易摔倒。
The sculptures were made using no supports, so they could fall over at any time.
VOA : special.2009.07.17
He would fall over the bridge onto the track right in the way of the trolley car.
他就会摔下桥,正好摔在电车轨道上挡住电车。
公正课程节选 : 耶鲁公开课
Six-month-olds don't, and even 12-month-olds don't find anything weird about this, while adults are sophisticated enough to understand that that's an unstable configuration and should fall over.
六个月大的婴儿则不会这么想,即使是十二个月大的婴儿,也没有发现这个木块存在的异常,只有经历世事的成年人才会理解,这不是个稳定的结构,而这个结构是会倒塌的
心理学导论课程节选 : 耶鲁公开课
Their muscles become stiff. They might bump into things or fall over objects.
VOA : special.2009.12.30
In warmer climates, snow is known to fall in areas over four thousand nine hundred meters above sea level.
VOA : special.2010.01.05
Techcrunch will likely see a big fall over the coming months after the recent drama there.
Taylor scored the fall over Appalachian State's Zachary Strickland to earn his spot in the quarterfinals.
Bearish sentiment, expectations that stocks prices will fall over the next six months, fell to 33.8%.