Four. Commonly made from heat-resistant nylon or polyester, the colorful, usually 80-foot-tall " balloon" part — called the envelope — is laid out on the ground preflight to be partially filled with cold air.

四、通常由耐热尼龙或聚酯制成，颜色鲜艳，通常有 80 英尺高的部分被称为“球囊”，它飞行前被放置地面上，使其部分空气。

And every one of the canals widens at its base into sac-like structures, called the utricle and saccule, which are full of hair cells that sense the motion of the fluid.

每一个管道部变宽，形成囊状结构，称为胞囊和球囊，它们了感知液体运动的毛细胞。

A balloon angioplasty might be done, which is a minimally invasive endovascular procedure where a deflated balloon is inserted into the blockage then inflated to open the artery up.

可以行球囊血管成形术，这是一个血管内的微创操作：将一个瘪球囊插入阻塞处，之后让它膨胀撑开血管。

Then, to create the lift required for takeoff, the air is heated by propane burners attached below the mouth of the envelope.

然后，为了创造起飞所需的升力，空气被附球囊下方的丙烷燃烧器加热。