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问题 选择题

下列关于胶体的说法正确的是（　　）

A．Fe（OH）3胶体具有吸附性，可用于净水

B．胶体与其它分散系的本质区别是胶体有丁达尔效应，而其它分散系却没有

C．胶体粒子的直径小于1nm

D．胶体的分散质可以通过过滤与分散剂分离

答案

A、Fe（OH）3胶体具有较大的表面积，具有吸附作用，可以净水，故A正确；

B、胶体与其它分散系的本质区别是分散质微粒的直径大小，故B错误；

C、胶体粒子的直径在1nm-100nm间，故C错误；

D、胶体的分散质和分散剂可以通过滤纸，不能分离，应用半透膜对胶体分散质和分散剂分离，故D错误；

故选A．

选择题

Your book is on the ____________ desk. [ ]

A. teacher

B. teacher's

C. teachers
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单项选择题

In January 2003, the Medusco Investment firm has decided to present its performance history in compliance with the Global Investment Performance Standards (GILES). Medusco was formed on January 1, 1992, and has never before presented its performance results in compliance with the GIPS standards. Which of the following actions must Medusco take in order to claim GIPS compliance（）

A. Present GIPS - compliant performance results for the 5 - year period from January 1, 1998, through December 31, 2002, and report five additional years of non - GIPS - compliant performance with a disclosure explaining why the performance in the earlier years is not GIPS - compliant.

B. Retroactively comply with GIPS for periods after January 1 , 2000, and report non - GIPS - compliant performance results for the periods January 1, 1993, through December 31, 1999, with a disclosure explaining why these earlier years are not GIPS -compliant.

C. Present GIPS- compliant performance results for the 5 -year period from January 1, 1998, through December 31, 2002.
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