Today’s article

“Riddle solved: Why was Roman concrete so durable?” — David L. Chandler, MIT News Office, January 6, 2023.

Original article: https://news.mit.edu/2023/roman-concrete-durability-lime-casts-0106

Free to read without login. This is a selected older article from January 6, 2023, not news published today. Read the full English text at the source; this page provides original learning exercises rather than reproducing the article.

Suggested level: B2–C1 (editorial estimate) · Time: 12–15 minutes to read, plus 8–10 minutes for the questions.

Introduction

古罗马混凝土为何经久耐用？今天练习梳理科学解释，区分过去的假设与实验依据。先读原文正文，再完成题目；无需阅读后面的媒体报道摘录。

Vocabulary

  1. aqueduct — 渡槽；输水渠
  2. durability — 耐久性
  3. ubiquitous — 普遍存在的
  4. quicklime — 生石灰
  5. exothermic — 放热的
  6. brittle — 易碎的
  7. recrystallize — 再结晶
  8. composite — 复合材料（此处为名词）

Reading comprehension

Answer questions 1–3 briefly in English. For questions 4–5, choose TRUE, FALSE, or NOT GIVEN according to the original article’s main text.

1. What did earlier explanations suggest the white lime fragments revealed?

Reference answer
Careless mixing or inferior ingredients.

2. How can water help repair a crack?

Reference answer
It reacts with the fragments, producing a calcium-rich liquid. Calcium carbonate can then crystallize and seal the gap.

3. How long did the experimental cracks take to close?

Reference answer
No more than two weeks.

4. The comparison sample without quicklime also stopped water from passing through.

Reference answer
FALSE. Its cracks remained unhealed, and water continued to pass through.

5. The article states the exact percentage by which this new formulation will reduce global emissions.

Reference answer
NOT GIVEN. Potential environmental benefits are discussed, but no quantified reduction is supplied.

Reading strategy

第 2 题画出“条件 → 过程 → 结果”的箭头链，再用自己的话概括。第 4 题标清对照样品。第 5 题检查数字究竟描述现状还是预测结果，避免把不同对象的百分比混用。

Expression practice

account for — 解释；说明原因。

Original practice sentence (not a quotation from the article): Differences in study habits may account for the gap between the two groups.

用 account for 写一句话，解释一次成绩变化的可能原因，并保留恰当的不确定性。