1,can---could
2,must---may
3,studied---studying
4,don't--won't
17,could't---can't
18,will---can
19,won't---does't
20,is't---hasn't
1,can---could
2,must---may
3,studied---studying
4,don't--won't
17,could't---can't
18,will---can
19,won't---does't
20,is't---hasn't