重金属检查中，加入硫代乙酰胺时溶液控制最佳的pH值是()

A．1.5

B．3.5

C．7.5

D．9.5

E．11.5

40. —Good evening. Huangshan Hotel.

—Good evening. ______________?

A．Do you still have a room for tonight

B．What would you like, please

C．Is there anything I can do for you

D．Who is that speaking, please