It has been announced recently that all the schools ________ not have the students attend school if the

students have high temperatures.[ ]

A．need  

B．shall

C．could  

D．ought to

（）技术是以光电子传感技术和激光技术为基础，由光学技术、电子技术、计算机技术和精密机械技术等密切结合而形成的一项高技术。

A、激光技术

B、电磁技术

C、传感技术

D、军用光电