British workers thus relied on a human alarm clock known as a “knocker-up.” 17 sticks or pea shooters, the human alarms would tour the streets, tap on windows, or blast them with dried peas, trying to wake paying customers in time for work.
答案：(C) Equipped with
過去分詞片語 Equipped with sticks or pea shooters（配備著棍子或豌豆槍），補充說明敲窗人的裝備；Aimed at（以……為目標）、Trained for（為……受訓）、Exhausted by（被……累垮）都不合。
句首是一個用逗號隔開的分詞片語，主詞在後面（the human alarms）。你可能困惑：為什麼用過去分詞 Equipped 而不是現在分詞？因為主詞和動詞之間是被動關係——人是「被配備上」工具的。equip 的用法是 equip sb with sth（為某人配備某物），人當主詞時就要用 be equipped with。
把分詞片語還原成完整子句最快：Equipped with sticks or pea shooters, the human alarms would tour the streets ＝ Because they were equipped with sticks or pea shooters, the human alarms would tour...。還原後 they were equipped 成立，語意也通。再看下一句 Whether they wielded rods or pea shooters（無論他們揮的是棍子還是豌豆槍），wielded（揮舞）確認了他們手上確實帶著這些工具。
Aimed at 是「以……為目標」，後面接目標不接工具；Trained for 是「為……受訓」，後面接受訓的目的；Exhausted by 是「被……累垮」，與後文「巡街、敲窗、專業地叫醒客戶」的積極描述相反。這三個選項的介系詞後面該接什麼，跟 sticks or pea shooters 這類工具都對不上。
equip sb with sth（為某人配備……）、be equipped with（配備有……）、equipment（設備，不可數）、be aimed at（以……為目標）、be trained for（為……受訓）、be exhausted by（被……累垮）。
The modern worker rolls out of bed, groans, and turns off an alarm clock before reluctantly getting up for the day’s work. But how did people get to work on time before alarm clocks were widely used? During the second Industrial Age, people toiled at unusual hours in mines or factories and often had to get up for work early in the morning. They 16 alarm clocks because adjustable alarms had been invented by the mid-19th century. But the new device was still relatively expensive and unreliable. British workers thus relied on a human alarm clock known as a “knocker-up.”
17 sticks or pea shooters, the human alarms would tour the streets, tap on windows, or blast them with dried peas, trying to wake paying customers in time for work. Whether they wielded rods or pea shooters, knockers-up became 18 throughout the United Kingdom. Every morning, these people, often older in age, were seen in big streets and small alleys, waking up their customers professionally. They usually would not leave people’s houses until they were sure their customers were awake.
While the practice continued in some parts of the country until the 1970s, it 19 as alarm clocks became more widespread and affordable. Today, beeping alarm clocks and smartphones that play morning music are surely simpler and more convenient. However, they cannot 20 the personal attention coming from the distinctive tap of a pea shooter.