At the beginning of class, the noise of desks _____ could be heard outside the classroom.

A．opened and closed

B．to be opened and closed

C．being opened and closed

D．to open and close

导游人员在引导旅游者旅行、游览的过程中，遇到可能危及旅游者人身安全的紧急情形时，在征得（）同意的情况下，可以调整或者变更接待计划，但是应当立即报告旅行社。

A.全体旅游者

B.多数旅游者

C.部分旅游者

D.少数旅游者