简答题 Write a note of about 50-60words based on the following situation：Paul，your English teacher from Australia，has asked you to help his son with his Chinese courses on Saturday.But you have to put it off to next week because youre preparing for an important job interview.Write a note to apologize and explain why you are not able to tutor his son this Saturday.
【参考答案】
Dec. 21 Dear Paul I'm afraid I can't tutor your son ......