5 Fill in the gaps with the proper grammar and lexical form of the word in brackets. Some scientists think that humans are biologically programmed be afraid of certain things, like the dark and n to(PoisoN) insects. Others are convinced that a frightening event in the past lies behind many phobias. A recent breakthrough in 2) (MEDICINE) research suggests that our memories can be rewritten and our fear erased. Scientists at New York University have found that a retrieved memory can be 3) (PERMANENT) changed. However, it appears that this is only possible within six hours of the memory emerging. After this time, the mind will simply form a second version of the memory. This means that in the future, in times of stress or(ORIGIN) fear memory could resurface. anxiety, the 4) Still, scientists are excited. Previously, they had thought that the human long-term memory was fixed and that the fears and phobias which hid inside it could only be treated with drugs. they may have discovered a much 5) (SAFE) way to prevent the return of fear
