On account of fuel supplies being finite and many people being wasteful, we will have to install ________ solar heating device in our home.

At the end of the race his legs ____ and he fell down on the ground.

Achieving a high degree of proficiency in English as a foreign language is not a mysterious ________without scientific basis.

Despite such a big difference in        towards what one eats，there is no doubt that people in the west regard the Chinese food as something special.

I have no ________ to the plan, so long as it would not cost too much.