The key answer of exercise 3

a)

1. much, far, considerably, slightly, infinitely, a bit, a lot, marginally, miles, not, way, a good deal, decidedly, significantly, barely any, loads
2. just, nothing like, nowhere near, not, every bit

b)

1. small difference → slightly, a bit, marginally, barely any; big difference → much, far, nothing like, considerably, infinitely, a lot, nowhere near, miles, way, a good deal, decidedly, significantly, loads; no difference → just, every bit (Not can be a small or a big difference.)
2. formal → considerably, infinitely, marginally, every bit, a good deal, decidedly, significantly; informal → much, just, far, nothing like, slightly, a bit, a lot, nowhere near, miles, way, barely any, loads (Way and loads are very informal and only used in spoken English; not is neutral.)

c)

1. 2 (progressive)
2. 1 (double)