bell jar

名词 bell jar:

1. a bell-shaped glass cover used to protect and display delicate objects or to cover scientific apparatus or to contain gases
   同义词：bell glass

1. If air weren't admitted into the bell jar, the electric bell in the bell jar would not ring because of a lack of a medium.
   如果我们不让空气进入铃罩，铃罩中的电铃一定会因缺少介质而不响了。