1.I am an engineer,( A )

1.I am an engineer,( A )
A.aren’t B.amn’t
有B这个写法么?
2.You ( B ) him so closely ; you should have kept your distance.
A.shouldn’t follow B.shouldn’t have been following
3.It is said that a new robot ( A ) by him in a few day.
A.will be disigned.B.will have benn designed
4.She will stop showing off if no notice ( A ) of her.
A.is taken B.will be taken
5.Diamond ( B ) in Brazil in 1971.
A.has been found B.was found
C.had been found
麻烦解释下``~