1... You can find out the reason for this f__________ (失败).

2... No one can a__________ (取得成就) anything without effort.

3... That rich man has a large staff of s__________ (仆人).

4... He made a v__________ (航海) to Australia last year.

5... O__________ (氧) is a gas without color, taste or smell, present in the air and necessary for us all.

6... The d__________ (密度) of the fog made it difficult to see where we were going.

 7... People of different r__________ (种族) may have different colors of skin, hair and eyes.

8..  The r__________ (逃跑的) slave was caught by his owner and was almost beaten to death.

9... “You never ask my opinion about anything,” Rod c__________ (抱怨).

10... S__________ (有经验的) teachers have the experience needed to make their lessons interesting.

1．It’s no use       （后悔）what you have done.                         

2．The little boy got       （分开）form h is parents in the dark.

3．The cooking time needed   （取决于）on the size of t he potato. 

4．A rainbow is a natural       （现象）.                                     

5．       （奇怪）they looked as if they were twins.                     

6．O       is a gas without color, taste or smell, present in the air and necessary for all forms of life on the earth.                 

7．To speed up the economy of the village, we should develop its natural r       , like

tourism.                                                                                  

8．F        is the second month of the year.                                  

9．School was over and I was both mentally and p        tired.       

10．It is generally a        that smoking is harmful to our health.