名詞 bell jar:

1. a bell-shaped glass cover used to protect and display delicate objects or to cover scientific apparatus or to contain gases
   同義詞：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.
   如果我們不讓空氣進入鈴罩，鈴罩中的電鈴一定會因缺少介質(zhì)而不響了。