Ответ:

British, foolish, childish (-ish)

• understandable (-able)

• heartless, pitiless (-less)

• successful, doubtful, useful, peaceful (-ful)

• experiment, treatment (-ment)

• musician (-ian)

• socialist, artist (-ist)

• capitalism (-ism)

• professional, industrial (-al)

• different (-ent)

• creative, attractive, active (--ive)

• dangerous (-ous)

• elementary (-ary)

• economic (-ic)

• director, worker (-or; -er)

• passage, marriage (-age)

• silence (-ce)

• freedom, kingdom (-dom)