3.line//annotation '=' will be line

= 4.imaginary line

1.mutiple line text

qwe
zuile

2.highlight

I am highlight

3.url

I am a url

1.list

• first
• second

2.two level list

• first
  • second

3.retract(缩进)

first

second

third

#Section 4:insert picture and code

1.

int main()
{
  return 0;
}