Use the proper article. Pay attention to the of-phrases:
a) 1. He leaned on ... back of... chair. 2. He saw the boy on ... roof of ... house. 3. ... neck of ... bottle was very narrow. 4. It was ... face of... old man. 5. ... cover of... book was very bright.
b) 1. He gave her ... little bunch of ... flowers. 2. I am looking for ... box of ... matches. 3. She joined ... group of ... students standing near by. 4. ... whole pack of ... cigarettes got wet and he couldn't smoke. 5. The house was reached by ... flight of ... steps. c) 1. She asked for ... glass of ... water. 2. We could see ... drops of... dew on the grass. 3. What do you say to ... bottle of... beer? --No beer, thanks, I prefer ... glass of ... mineral water or just ... cup of ... tea. 4. He took ...
jug of ... milk standing on the kitchen-table and poured himself a little. 5. Here's ... piece of ... chalk for you to write with.