Spider Webs
练习内容
There are many kinds of spiders, but they all have one thing in common. They all make silk. Spider silk is very strong. Some spiders use it to build spider webs and to help them climb. What do they us
There are many kinds of spiders, but they all have one thing in common. They all make silk. Spider silk is very strong. Some spiders use it to build spider webs and to help them climb. What do they us