1.man后面加 who
2.student后面加who
3.which-that
4.who's-whose
5.去掉it
6.were-was
7.which-when
8.have-has
9.whom-who
10.machine后面加 whichthat
11.which-that
12.that-who
13.whom--that
1.man后面加 who
2.student后面加who
3.which-that
4.who's-whose
5.去掉it
6.were-was
7.which-when
8.have-has
9.whom-who
10.machine后面加 whichthat
11.which-that
12.that-who
13.whom--that