18．用方框内所给单词的适当形式填空，每词限用一次．
| success difficult convenient stand nine |
66．Mr Black lives in the centre of the city，it's veryconvenient．
67．Mary likes to walk to theninthfloor every day．It's good for her health．
68．Only practice can make you asuccessful person
69．Some students don't know how to face the heated competition．
We have to beat thedifficulty．
70．When I looked up，I saw my best friends and teammatesstanding there and cheering for me，with their eyes filled with care and encouragement．
