A huge amount of oil was spilt on the East Sea,the causes of ________ are still under investigation.
I was about to leave the office ______ an unexpected visitor came.
--- It took me two hours or so to walk here. --- But you ______ here in Billy’s car.
Jack climbed ______ to the top of the mountain though he is only a boy of ten.
I don’t think he can pay off all the debt when he gets paid, ______?
Last night, they succeeded ______ the fire ______.