问题
选择题
When you come into the exhibition hall，you can see a large board with a notice on it，saying visitors__________not to touch the exhibits.
A．will request
B．request
C．are requesting
D．are requested
答案
D
“request sb.(not)to do sth.要求某人(不要)做某事”是固定结构,根据题干,应使用被动语态。