11._______ from the outer space， our earth looks like a water-covered ball.
A. Having seen
B. Seeing
C. Seen
D. Having been seen
12.I don‘t mind _______ the decision as long as it is not too late.
A. you to delay making
B. your delaying making
C. your delaying to make
D. you delay to make
13.The picture _______ on the wall is painted by my nephew.
A. having hung
B. hanging
C. hangs
D. being hung
14._______ such heavy pollution already， it may now be too late to clean up the river.
A. Having suffered
B. Suffering
C. To suffer
D. Suffered
15.They pretended to be working hard all night with their lights _______.
A. burn
B. burnt
C. burning
D. to burn
