Geometry: Left Fist Rule

Stop using right hand rule, use LEFT FIST RULE. And remember, your thumb is always in your fist covered by your four fingers.

Calculus: Integral

Calculus II, special thanks to professor [Wenzheng Shi](https://sites.google.com/view/wenzhengshi/) who provided me with excellent exercises!

Reading

Using Verb and Logic to read a passage