幫我解決下列英語問題（最好有詳細解釋）
1.For the success of the project ,the company should__the most of the opportunities at hand.
A.obtain B.grasp C.catch D.make （答案選D,為何不選B）
2.He began by making a few general observations__the report.
A.towards B.about C.of D.with(答案選B為何不選C)
3.The chairman of the company said that new techniques had__improved their production efficiency.
A.violently B.severely C.extremely D.radically（答案選D,為何不選C）
4.__mainly for the invention of the telephone,Alexander Graham Bell devoted his life to helping the deaf.為何不選A）
A.Though remembered B.While remembering
5.It is imprpbable that he will ever again in his life__so much without having to do anything in return.
A.give B.to give C.be given D.to be given(答案選C)
6.He should__ his own living.
A.operate B.manage C.handle D.earn(答案選D,為何不選B)