语篇阅读(小学)Is spider silk really strong?

Is spider silk really strong？You can often find a spider web(网) in the corner of an oldhouse or in a tree. It is usually easy to break one with just your fingers.

But did you know? Spider silk is one of the strongest naturalmaterials (天然材料) in the world.It can be even stronger thansteel (钢). How is spider silk soeasy to break when it's stronger than steel?

It's all because...

The silk is really, really, reallythin! It is just 0.003 millimeters(毫米) wide. That's more than 20times thinner than a hair on your head.

What if the spider silk getsthicker?

If it is as thick as a steel wire (钢), it is 100 times harder tobreak than the steel wire. If it isas thick as a pencil, it can pull an airplane.Biggest and strongest web.

The web of a Darwin's bark   spider (达尔文树皮蜘蛛)is as  wide as 25 meters. It is as long  as two city buses. The spider can   cross a river on its web. Its silk is  also stronger than any other  spider's.