Давайте заполним пропуски А—F указанными частями предложений:
A 6. who must have missed class.
B 2. when they pass us in the doorway.
C 1. where the aim is to be unpleasant to the other person.
D 7. who are willing to make our lives more pleasant.
E 5. while others seem incapable of emitting a single sign.
F 3. who are unable to build bridges of affection.
Таким образом, лишняя часть: 4. that are beyond people's reach.