Examination

I am wondering, why they did badly in their examination?

Same questions are given. Solutions are given as well. Hints are provided also. However, they still did wrongly. What is the problem?

Lazy of not revising properly? Not understand of my teaching? Not talented in studying the subject?

1 A, 1 B+, 1 C+, 2 C and 1 D. These are the best I can give you. Please show me your effort, OK?