The chinese knew how to produce silk by about 2700 bc
a. true
b. false

True, The Chinese knew how to produce silk by about 2700 BC.

Explanation:

The legend of the discovery of silk says that the wife of the yellow emperor Leizu thought about using silk while she was drinking tea. The legend says that she was having tea and a cocoon of that moth fell into his tea, then she discovered that the cocoon was made of strong and thin thread. So, she wondered what would happen if she combined many of these threads. She experimented and she created "silk". The legend also says that she developed the silk cloth.

But, there is evidence of early china that suggests that it was used back in the 4000 BC. Excavations found a cocoon cut in half by a sharp knife and samples of fabric from later on. The place where they found this evidence is Xia county, where the Yangshao culture developed.

just finished this it is b. centrifugal force

by 1880, germany had more rail lines than great britain and russia.