临汾有要藏獒的吗:win与gain等等还有好多问题,谁懂?帮忙解释一下,谢谢

1.Many doctors pratie decption of their patients,but not Philip.He believes that it pays,____,to be honest with patients.
A.in final B.by the end C.in the first place D.in
the long run
答案是D,为什么?这句话什么意思?
2.When he was a young man,he travelled about the world__.
A.on its own B.of its own C.on his own D.of his own
答案是D,为什么?并翻译一下句子
3.There were people of every political belief at
university,ranging___from communists to capitalists.
A.all the way B.all over C.all the time D.all right
答案是A,为什么啊?怎么理解这答案的意思
4.The demand of China-made cotton products in the international market is now ____.
A.in the rise B.on the rise C.in a rise D.on a rise
答案是A,为什么?有什么讲法,其他几个有什么区别,为什么不对?
5.-There will be a football match between Class One and Class Two this afternoon.
-I'm sure Class One will _C_ the match.
A. beat B.win C.gain D.earn
答案为什么是C,而不是B?