1. The Smith family are inscrutable folks. They don't like to be around other people. When they are around others they never speak.2. Math is so hard to me.3. Physics is hard to understand.
 inscrutable hard to understandinscrutable 可用在難懂的事物上面
Student protesters against the Cross-Strait Service Trade Ageement have occupied Taiwan's legislature and are staging a sit-in.