Riddles – Exercises for Class 4 Q. Solve the following riddles. I am a fruit with a crown on my head.Teachers use me to erase the blackboard.I am green. I can be sweet as well as sour. A fox thinks I am sour. Can you guess who I am? Answer pineappledustergrapes Related posts: Editing Exercises for Class 10 Pronouns – Exercises for Class 3 Simple Future Tense – Exercises for Class 5 Will or Shall – Exercises for Class 5