Older people often fall becausethey are too weak to brace themselves, and they have trouble with stepsand opening jars because their muscles have lost so much strength.

老年人之所以经常跌倒是因为他们虚弱到没法保持身体平衡，而软弱无力的肌肉也使得他们上楼梯和开罐头变成了一件难事。