n. 减少【计】 减法【经】 减除数, 减去

attack/defend/attract/tractor/attractive/attraction/contract/subtraction/abstract/concrete
记忆：
1. attack [ E5tAk] n. 进攻, 攻击, (用语言)抨击, 疾病发作 vt. 攻击, 抨击 Another fierce attack will be waged soon. 他们将很快发动又一次猛烈的进攻。
2. defend [ di5fend ] vt. 防护, 辩护, 防卫 The whole nation will do what it can to defend the national unity. 全民族会竭力保卫国家的统一。
3. attract [ E5trAkt ] 词根tract表示“拖，拉” vt. 吸引 Her outstanding beauty always attracts pedestrians’ eyes. 她出众的美貌总会吸引路人的眼睛。
4. tractor [ 5trAktE ] n. 拖拉机 The tractor is helpful on our farm.我们农场上拖拉机很有用。
5. attractive [ E5trAktiv] adj. 吸引人的, 有魅力的 A person with humor is often attractive. 有幽默的人经常能吸引别人。
6. attraction [ E5trAkFEn ] n. 吸引, 吸引力, 吸引人的事物 Eastern Eden is sure to be another tourist attraction. 东方伊甸园肯定又是一个吸引游客的地方。
7. contract [ 5kCntrAkt] con-, 一起；contract, 拉到一起，大家要遵守，n. 合同, 契约 The contract will expire at the end of this month. 合同本月底到期。
8. subtract [ sEb5trAkt] sub-，下面，拖拉到下面去， v. (～ from)减去, 减 What can you get if you subtract five from ten?从十里减去四你会得到多少？
9. subtraction [ sEb5trAkFEn ] n. 减少 That’s a simple subtraction. 那是一道简单的减法。
10. abstract [ 5AbstrAkt ] ab-stract 抽出来的，抽象的 How can such a young boy understand such an abstract question?这样小的男孩怎么能理解这样抽象的问题？
11. concrete [ 5kCnkri:t ] adj. 具体的, 有形的 n. 混凝土 Can you give us some concrete examples?你能给我们举一些具体的例子吗？
另类阅读：
The attractive resources in our country may attract many greedy eyes. They wish to sign contracts to take our riches away in their tractors. If we refuse, they may take them by force. We must defend our country when they attack our country.