【题目】This machine is very easy . Anybody can learn to use it in a few minutes.
A. operating
B. to be operating
C. operated
D. to operate

【答案】D
【解析】句意：这个机器很容易操作。任何人在几分钟内能学会使用。在句型“主语+be+adj+to do”中，如果这个主语是动词do的逻辑宾语，故用主动表被动，所以选D。