4道英语选择题的解释（正确答案已给出,只需说出选那个答案的理由）

4道英语选择题的解释（正确答案已给出,只需说出选那个答案的理由）
（B）___of people have never been there.
A,Three fourth B.Three-quarters C.Three-fourth D.Third-four
(B) Our life has greatly changed here since___.
A.the seventieth B.the seventies C.seventy years D.the past seventy
(A)There ___two minutes left.
A.are B.is C.have D.has
(B)There are ____in the garden.
A.a kind of flower B.all kinds of flowers C.a few kind of flowers D.a few kinds of flower
·请说出每道题为什么要选那个答案,越明白越好,我会给出相应的追加分!