定向资产管理业务的特点为：证券公司与客户必须是一对一的投资管理服务；具体投资的方向在资产管理合同中约定；必须在单一客户的专用证券账户中封闭运行。（）

—I’m told that our plane will at least delay 3 hours.

—What do you think has happened?

—It is said to have been _______ by a terrible storm.

A．held out

B．held in

C．held on

D．held up