1·What goes on in a cocoon as a caterpillar changes into a butterfly remains one of nature's best kept secrets.
当毛毛虫变成蝴蝶的时候，茧里发生了什么仍然是自然界最大的秘密之一。
2·He tucked the coal into the center of the clockwork, and placed it all on the skin, and wrapped it up and tight it into a cocoon shape.
他把煤块塞进钟形装置的中心，并全部放在表壳上，然后紧紧地裹成一个茧状。
3·So the man decided to help it. He took a pair of scissors and snipped off the remaining bit of the cocoon.
这个人决定帮助它，他用剪刀把茧的剩余部分剪开，蝴蝶宝贝很轻松地钻了出来。
4·The symbiotic bacteria secrete a mixture of antimicrobial compounds on the walls of the cocoon to ward off microbial threats.
共生细菌在茧壁上分泌一种抗菌物质混和物，以抵抗因细菌引起的威胁。
5·Only in struggling to emerge from a small hole in the cocoon does a butterfly form wings strong enough to fly.
只有在茧中奋力地撑出了小洞，一只蝴蝶才能拥有足够强劲的翅膀用以飞翔。