In certain situations such as in crowded subway cars or elevators, it is not always possible for people to keep their 13 distance from others.
答案：(C) preferred
空格夾在所有格 their 與名詞 distance 之間，須填形容詞，preferred 是過去分詞轉品當形容詞「偏好的」：在擁擠的車廂或電梯裡，人們不見得能與他人保持自己偏好的距離；prefer、preferring、being preferred 都不合。
答對率 21%。
prefer 這個動詞你很熟（prefer A to B），但很少把 preferred 當成一個形容詞記住：「偏好的、首選的」。
所有格 their 與名詞 distance 之間，只能放形容詞。四個選項中只有 preferred 具備形容詞功能。
preferring 是現在分詞、帶主動意味，會變成「正在偏好的距離」——但距離不會自己去偏好誰，方向錯了。通則是：被修飾的名詞若是「做動作的」用 -ing，「被做動作的」用過去分詞。distance 是被人偏好的對象，所以用 preferred。
preferred method（首選方法）、the required documents（必備文件）、reserved seats（預留座位）、a designated area（指定區域）。
preferred distance／method（偏好的距離／首選方法）、prefer A to B（喜歡 A 勝過 B）、personal space（個人空間）。
Have you been irritated by someone standing too close in line, talking too loud or making eye contact for too long? Or, they may have 11 you with the loud music from their earphones, or by taking up more than one seat on a crowded subway car. You feel unhappy because your personal space has been violated.
According to scientists, personal space involves certain invisible forces imposed on you through all the 12. For example, people may feel their space is being invaded when they experience an unwelcome sound, smell, or stare.
In certain situations such as in crowded subway cars or elevators, it is not always possible for people to keep their 13 distance from others. They learn coping strategies to deal with their discomfort. For instance, people often avoid eye contact with someone standing 14 them, or they pretend that these people are lifeless objects in their personal space. Given the opportunity, they may 15 to a corner, putting distance between themselves and strangers. Or, they may sit or stand equidistant from one another like birds on a wire.