16.
(A) must be using
(B) could have used
(C) had hardly used
(D) were mostly using

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 could have used 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.” Equipped with 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.

現代工人從床上爬起來，呻吟著，關掉鬧鐘，然後不情願地起床開始一天的工作。但是，在鬧鐘被廣泛使用之前，人們是如何準時上班的呢？在第二個工業時代，人們在礦山或工廠裡加班加點地工作，經常不得不一大早起床上班。他們本可以使用鬧鐘，因為可調鬧鐘在 19 世紀中葉就已發明。但新設備仍然相對昂貴且不可靠。因此，英國工人依靠一種被稱為 "敲鐘人 "的人力鬧鐘。配備棍棒或豌豆彈弓的人力鬧鐘會在大街小巷巡視，敲打窗戶，或用乾豌豆射窗戶發出刺耳的高音，試圖及時叫醒付錢的顧客去上班。