Directions :

Your company is planning to hold a meeting in a hotel. Write a letter to the hotel manager to

1) book a conference room and

2) ask them to make some necessary preparations.

You should write about 100 words on ANSWER SHEET 2. Do not sign your own name at the end of the letter. Use "Li Ming" instead. You don’t have to write the address.

旋转机器产生不平衡振动的主要原因有哪些？