21.

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

22.

1. in respect of
2. in favor of
3. in terms of
4. in the light of

23.

1. so far
2. so forth
3. sooner or later
4. far from

24.

1. what of
2. of
3. which of
4. that of

25.

1. make up of
2. make up
3. make for
4. make out

26.

1. quarrel
2. battle
3. debate
4. argument

27.

1. future losses
2. further losses
3. dead losses
4. great losses

28.

1. claim
2. declaim
3. declare
4. proclaim

29.

1. material
2. materials
3. resource
4. resources

30.

1. buy up
2. bring up
3. buy off
4. buy in

(Reference keys.)