1.

1. if
2. unless
3. even if
4. because

2.

1. like
2. likely
3. less likely
4. more likely

3.

1. rest
2. other
3. fittest
4. fitter

4.

1. active
2. lively
3. still
4. inactive

5.

1. to exercise
2. exercising
3. exercise
4. exercised

6.

1. However
2. So
3. Although
4. Furthermore

7.

1. reduce
2. reducing
3. to reduce
4. reduced

8.

1. encouraged
2. encouraging
3. to encourage
4. encourage

(Reference keys.)