Whenithasbeendecidedwherewearegoingtodrill,weputupatthesurfaceanoilderrick.这是什么句型?

Question

When it has been decided where we are going to drill, we put up at the surface an oil derrick.
这是什么句型?

Answer 1

这里when引导的时间状语从句中,it是形式主语,真正的主语是where we are going to drill,就是说本来应该这样说when where we are going to drill has been decided,has been decided是现在完成时的被动语态,此句意思为“当钻井地点被定下来之后”；而后面的主句是谓语动词和宾语被地点状语分隔开了,即we put up at the surface an oil derrick=we put up an oil derrick at the surface an oil derrick.这是英语的常见现象.