.This is the small house less than 15 square meters,under _____ roof lives a large family of three generations.
71. People eat a lot of sugar __________ cakes, soft drinks, sweets and so on every day.
70. I know it is difficult __________ him to talk like the lecturer, but I think he should grasp every chance .
69. With the guide leading the way, the visitors were able to travel through the forest not by air but _____ foot.
68. When the boy playing by the river fell into the river, I was out of the room _______.
67. The Prime Minister was more fit __________ his office than anyone else.