The young engineer sat down on a rock and rested his head in his hands. He would never get home; it was 1 . For weeks he had been 2 in the Northwest Canadian forest. Now there was a terrible 3 behind his eyes， and worse of ail， he had gone 4 .

Suddenly a man 5 out of the woods， an Indian who had been hunting in the area. Seeing the engineer's 6 ， he caught a fish in a nearby 7 and fed the sick man the 8 of the fish and some flesh from its head. 9 within a few hours the engineer's pain was 10 . A day later he could 11 again， and the next day he had 12 recovered.

When he returned home， the engineer told the 13 to Dr Price. Not until years later did it become a(n) 14 fact that this was just an everyday 15 doing its work. For what the engineer did， by eating fish eyes， was to 16 his vitamin (维生素)。

Vitamin A's biggest job is to keep the eyes 17 . Without A， people and animals get night blindness and other eye problems. Without A， people can even be totally blind. A helps to keep the skin in good 18 . A also helps 19 with bones and teeth and has to do with proper 20 of blood cells.

1. A. hopeless B. useless C. careless D. timeless

2. A. lost B. treated C. hunting D. working

3. A. scene B. illness C. pain D. heat

4. A. blind B. changed C. mad D. separated

5. A. reached B. appeared C. hid D. watched

6. A. starvation B. situation C. reality D. trouble

7. A. stream B. boat C. place D. sea

8. A. tail B. skin C. bone D. eyes

9. A. Possibly B. Surprisingly C. Fortunately D. Immediately

10. A. shown B. gone C. settled D. disappeared