a. 2. can't be 3. must be 4. might be doing/could be doing 5. can't have been 6. must have been 7. might have gone 8. might not have thought 9. should be.
b. 2. the disease is likely to 3. you will probably be able to 4. is unlikely to be 5. we are bound to 6. It's very unlikely that 7. she's bound to be 8. she will definetely.