You are assigned as the project manager to a project which is executed for a customer under FP contract. Your customer informed you this morning that they insist on certain "refinements" of the project scope. You agree that the requested actions make really sense to the project, but believe that they constitute a major change increasing the project scope. What should you do next

A) Accept the request of the customer. Diligently document the additional costs and working hours spent by yourself and the team on the implementation of the change and invoice these to the customer at appropriate rates.
B) Perform earned value analysis to assess the current status of the project and get all the numbers you need to communicate the case to the change control board which then will have to make the best decision regarding the customer request.
C) Check the contract, the project charter, the scope statement and other documents related to the project and the contract. Assess the impacts of the scope change. Then discuss the situation with the project sponsor and the change control board.
D) Talk to the project sales department and find a joint solution with them how to best reject the request considering the commercial and strategic value of the customer to the organization you are working for.

散射和绕射的发生是有所区别的，其主要区别有（）。

A.发生散射的条件为障碍物的大小明显小于波长

B.发生绕射的条件为障碍物的大小明显小于波长

C.发生散射时，小障碍物不成为新的声源，不再发射超声波

D.发生绕射时，超声波仅绕过障碍物的边缘行进

E.散射时探头接收到的散射回声强度与入射角无明显关系