Most puter users think it necessary for their software regularly.
A. to up date
B. to be updated
C. to have been up dated
D. to have updated
网友回答
A. to up date
(答案→)B. to be updated
C. to have been up dated
D. to have updated
解析:句意:大多数电脑使用者认为按时更新他们的软件是很必要的。这里it是形式宾语,不定式是真正的宾语,“他们的软件”和“更新”之间是被动关系,故用被动语态;且表示经常或反复发生的动作,故用不定式的一般式,选B。