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.