Since the 1970s, book towns like Hay on-Wye 12 up all over the world.
答案：(D) have been springing
現在完成進行式 have been springing，配合 Since the 1970s（自從1970年代起，持續到現在），spring up 表示「湧現/興起」；spring（現在式，不符合持續性）、sprang（過去式）、had sprung（過去完成式，沒有更早的過去參照點）都不合。
你看到 Since the 1970s 就知道要用完成式，但選項裡有 sprang（過去簡單式）、had sprung（過去完成式）、have been springing（現在完成進行式），三個都跟「過去」有關，一時分不出來。關鍵在 since：since ＋ 過去時間點，時間軸一定是從那個點一路連到現在，所以只能配現在完成式或現在完成進行式。
句意是「自 1970 年代以來，像海伊鎮這樣的書鎮在世界各地不斷冒出來」——這件事從 1970 年代開始，到現在還在發生，而且強調「不斷、持續」，所以用現在完成進行式 have been springing。動詞片語 spring up 是「如雨後春筍般湧現、興起」。
spring 是現在簡單式，只講常態，接不上 since 帶出的時間跨度；sprang 是過去簡單式，會把整件事關在過去、與現在無關，正好和 since 衝突；had sprung 是過去完成式，必須有「另一個更早的過去時間點」當參照，本句沒有這個參照點。看到 since ＋ 過去時間，先把純過去式和過去完成式刪掉，選項通常就只剩一兩個。
spring up（如雨後春筍般湧現）、since ＋ 過去時間點（自從……以來）、have been Ving（現在完成進行式，一直在……）、for ＋ 一段時間（達……之久）、pop up（突然冒出來）、sustainable development（永續發展）。
A book town is a rural town in which second-hand and antiquarian bookshops are concentrated. The concept was 11 by Richard Booth, who opened the first second-hand bookshop in Hay-on-Wye, UK in 1961. Following him, many local people opened their own bookshops, and the small town soon became a model of sustainable rural development and tourism.
Since the 1970s, book towns like Hay on-Wye 12 up all over the world. Although all book towns have a great number of bookshops, that's where the similarities 13 . Each of these towns shows unique features of its own. Some have many small private shops, while others have organizations steered by volunteers. Some even run regular activities to attract visitors. For example, an annual book festival is held in Hay-on-Wye. Clunes, in Australia, holds a monthly book talk that hosts authors to discuss their latest 14 .
As digital reading is changing our traditional way of reading, book towns like Hay-on-Wye are particularly important to 15 . The feel of a book, the smell, the weight, and the knowledge that a particular book might be more than a hundred years old—all these highlight the importance of preserving the physical book as a complement to technology.