单选题：The next thing he saw was smoke ________ from behind the hou..

The country has already sent upthree unmanned spacecrafts, the most recent at the end of last March.[ ]A．has been launchedB．having been launchedC．being launched D．to be launched

Recently a survey ________ prices of the same goods in two different supermarkets has caused heateddebate among citizens.[ ]A. comparedB. comparingC. comparesD. being compared

____ at a decision, they immediately set to work. [ ]A. ArrivingB. ArrivedC. Having arrivedD. Having been arrived

Examples of people____ by lightning more than five times are almost common. [ ]A. strikingB. to be struck C. being struckD. struck

He asked who was the man ____ on. [ ]A. to be operating B. operating C. to operate D. being operated