GRE閱讀真題及解析：
A decrease in face-to-face social contact can precipitate depression. Time spent using the Internet cannot be spent in face-to-face social contact, so psychologists have speculated that sharply increasing Internet use can cause depression. Studies of regular Internet users have found a significantly higher incidence of depression among those who had recently doubled the amount of time they spent using the Internet than among those whose use had not increased. Hence, the psychologists’ speculation is correct.
1. Which of the following is an assumption on which the argument depends?
A. In general, the reason that the people in the studies had doubled their Internet use was not that they had earlier experienced a significant decrease in opportunities for face-to-face social contract.
B. A sharp decrease in face-to-face social contact is the only change in daily activity that can lead to an increased incidence of depression.
C. Using the Internet presents no opportunities for people to increase the amount of face-to-face social contact they experienced in their daily lives.
D. Regular Internet users who are depressed will experience an immediate improvement in mood if they sharply decrease the amount of time they spend on the Internet.
E. Before they doubled the time they spent on the Internet, the people who did so were already more prone to depression than are regular Internet users in general.
解析
答案：C
解析：題目問(wèn)文章論證基于的假設(shè)。
文章中心結(jié)論是中間這句：so psychologists have speculated that sharply increasing Internet use can cause depression 增加上網(wǎng)時(shí)間會(huì)引起抑郁。
文章理由以該句結(jié)論為界，分為前后兩個(gè)部分：前半部分理由看起來(lái)是一個(gè)鏈狀推理：減少面對(duì)面社交會(huì)引起抑郁。用來(lái)上網(wǎng)的時(shí)間不能用于面對(duì)面社交。后半部分理由是一個(gè)對(duì)比研究：近增加兩倍上網(wǎng)時(shí)間的常規(guī)網(wǎng)絡(luò)用戶比沒(méi)有增加的常規(guī)網(wǎng)絡(luò)用戶有更高的抑郁發(fā)生率。前后兩半部分理由到結(jié)論各需要什么假設(shè)?或者，各自推理在何種情況下會(huì)不成立?
先說(shuō)后半部分。這個(gè)對(duì)比研究支持結(jié)論需要什么假設(shè)?對(duì)啦?實(shí)驗(yàn)前、實(shí)驗(yàn)中沒(méi)有其他干擾變量啦!
前半部分呢?看出來(lái)了么?它貌似一個(gè)鏈狀推理，但它與嚴(yán)密支持結(jié)論的鏈狀推理之間是有出入的。
這樣一個(gè)鏈狀推理才是嚴(yán)密的，無(wú)懈可擊的：
理由1：減少面對(duì)面社交會(huì)引起抑郁
理由2：增加上網(wǎng)的時(shí)間會(huì)減少面對(duì)面社交時(shí)間
結(jié)論：增加上網(wǎng)時(shí)間會(huì)引起抑郁
對(duì)啦!問(wèn)題是：即使用來(lái)上網(wǎng)的時(shí)間不能用于面對(duì)面社交，但是否能增加每天其他時(shí)間的面對(duì)面社交機(jī)會(huì)呢?比如，俺上網(wǎng)用來(lái)dating, 上網(wǎng)之后意猶未盡，相約面對(duì)面熱聊啦!如果出現(xiàn)這種情況，原文推理就不是我們需要的嚴(yán)密推理啦!所以，文章推理依據(jù)的假設(shè)就是要排除這種情況。就是C選項(xiàng)啦!
至于你所糾結(jié)的B選項(xiàng)，原文推理只需要一個(gè)充分條件：減少面對(duì)面社交一定會(huì)引起抑郁，不需要B選項(xiàng)所表達(dá)的必要條件啦!
還有，A選項(xiàng)是針對(duì)文章中哪一部分推理?對(duì)啦!后半部分!后半部分對(duì)比研究到結(jié)論不需要這個(gè)假設(shè)，為什么?如果你想明白，就不用再參加什么培訓(xùn)啦!你對(duì)GRE閱讀，至少是邏輯單題部分理解已經(jīng)很到位啦!