1 . He was giving his collection ______ for nothing.

2 . After my explanation, Mandy still had a ______ (puzzle) expression on his face.

3 . The world governments are becoming increasingly ______ (concern) about   rising   global   temperature levels.

4 . When the old man was hit by the car, all ______ (passer-by) just stood by but only Jack came to rescue.

5 . The team developed ______ (advance) techniques for measuring and controlling the noise of the machine.

6 . The doctor claimed ___________ (discover) a cure for the disease.

7 . ___________ (determine) to make his fortune in South America, he set off from his home for New Orleans.

8 . Last Monday, I ___________ (get) around in the street when I saw an old man fall off his bike.

9 . Rogers took ___________ painting for a while, but soon lost interest.

10 . My wallet is nowhere to be found. I must ___________ (drop) it when I was on the bus.