1.

1. of ... on ... of
2. of ... in ... of
3. from ... on ... from
4. from ... in ... from

2.

1. which
2. /
3. where
4. that

3.

1. /
2. in
3. to
4. at

4.

1. will leave
2. is leaving
3. leave
4. have left

5.

1. after
2. in
3. on
4. before

6.

1. at
2. for
3. of
4. on

(Reference keys.)