umbrella [ʌmˈbrelə] n. 雨伞
英英解释（牛津词典）：
an object with a round folding frame of long straight pieces of metal covered with material, that you use to protect yourself from the rain or from hot sun
umbrella的特点：
- 一种物品（an object）
- 它有圆形可折叠的框架，由长而直的金属块构成，上面覆盖有材料（with a round folding frame of long straight pieces of metal covered with material）
- 你用来保护自己不受雨水或炎热的太阳（that you use to protect yourself from the rain or from hot sun）
