Интерактивное упражнение доступно по этой ссылке: Shade or Shadow? (ответы в нем проверяются автоматически). 

Если вам по каким-либо причинам не хочется использовать удобное и приятное интерактивное упражнение, то ниже находится простая текстовая версия. 

1. We sat down in the __________  of the wall.
2. The industry is a pale __________  of its former self.
3. Children were having fun, chasing each other's __________.
4. The ship's sail cast a __________  on the water.
5. The temperature can reach 40°C in the __________.
6. These plants grow well in sun or __________.
7. The __________ lengthened as the sun went down.
8. The word has many __________ of meaning. 
9. He didn't want to cast a __________  on their happiness.
10. She knew beyond a __________  of a doubt that he was lying. 
11. She looked pale, with deep __________ under her eyes.
12. He threw out his old suits, all in various __________ of brown. 
13. Her eyes were a delicate __________  of green. 
14. The candles on the table threw huge flickering __________ against the wall.

 Ключи:

1. shade
2. shadow
3. shadows
4. shadow
5. shade
6. shade
7. shadows
8. shades
9. shadow
10. shadow
11. shadows
12. shades
13. shade
14. shadows