碘是人体必需的微量元素，长期缺碘可导致碘缺乏症。但“一刀切”地补碘又会使有些人摄碘过

Many trees and flowers ________ in our city every year.

A．planted

B．are planted

C．were planted

D．plants

It was not until I came here _______ I realized this place was famous for not only its beauty but its weather.

A．who

B．that

C．where

D．before

因维生素D缺乏引起的障碍性骨病是（）

A.痛风

B.侏儒症

C.佝偻病

D.呆小症

E.大骨节病

根据评价结果对隔离开关和接地开关进行缺陷处理，处理时无需涉及更换的检修工作为（）检修。

A.A类

B.B类

C.C类

D.D类

数字证书采用公钥体制，即利用一对互相匹配的密钥进行（）

A.加密

B.加密、解密

C.解密

D.安全认证