Tom is said a new computer program recently.but I don't know when he'll finish i

Tom is said ________ a new computer program recently，but I don't know when he'll finish it.

A．to design  　B．to be designing

C．to have been designing  　D．to have designed

试题答案

C　考查不定式的时态。句意：据说汤姆最近在设计一种新的电脑程序，但我不知道他什么时候完工。后半句暗示“设计”这一动作还在进行，故用不定式的现在完成进行式。