Homework∠ Exercise 30Aon Pages 508-509 Exercise 30B on pages 510-511 Exercise 30C on Pages 514-515 ■预习第31讲(516-540页) ■预习第32讲(541-569页)Homework ◼ Exercise 30A on Pages 508-509 ◼ Exercise 30B on Pages 510-511 ◼ Exercise 30C on Pages 514-515 ◼ 预习第31讲（516-540页） ◼ 预习第32讲（541-569页）