2. If the sun shines, we go for a walk.

If the sun shines, we’ll go for a walk.

If the sun shone, we went for a walk.

3. If we have time, we visit our friends in London.

If we have time, we’ll visit our friends in London.

If we had time, we visited our friends in London.

4. If you eat lots of sweets, you have a toothache.

If you eat lots of sweets, you’ll have a toothache.

If you ate lots of sweets, you had a toothache.

5. If they invite their best friends, they cheer them up.

If they invite their best friends, they’ll cheer them up.

If they invited their best friends, they cheered them up.