资讯

A simple sneeze can travel up to 100 miles an hour and spray a cloud of 100,000 germs. Sounds gross, but sneezing is actually a protective reflex that's designed to keep you healthy. It begins ...
A simple sneeze is often all it takes for viruses to ... This short film is from the BBC series, Inside the Human Body. This short film gives students an idea of the workings of the immune system.