题目

在艾滋病病毒(HIV)最初侵入人体时，HIV会迅速繁殖，人体免疫细胞在受到HIV攻击时也会迅速增多，并摧毁大多数HIV，但不能将其彻底消灭。HIV经过一段时间的潜伏繁殖，逐步侵袭人体的免疫系统(即人体抵抗各种外来感染的自然防卫系统)，降低并最终破坏人体的免疫功能。下列表示HIV感染人体后，体液中HIV浓度和免疫细胞浓度的变化过程，其中正确的是( ) A . B . C . D . 阅读理解 阅读下面的短文，从各题所给的四个选项（A、B、C和D）中选出最佳选项。 　　Across the globe, single parent homes are on the rise. In the US, the 2000 census (人口普查) showed 24.8 million, or nearly 24 percent of the nation's 105.5 million households, were traditional two-parent homes. By comparison, 9.8 million households, or 9 percent of all US households were headed by an adult raising a child alone. The 1990 census showed 26 percent of homes were led by a married mother and father, and 8 percent of homes were led by a single parent. 　　Similar increases occurred in other countries. In the UK, lone-parent homes increased from 3.3 percent in 1990 to 5.5 percent in 1999. Single parent households in Australia rose from 5.8 percent in 1990 to 7.6 percent in 1999. Belgium saw the increase from 1.8 percent lo 2.7 percent during the same period of time. These countries tend to have greater acceptance of the single parent because there are fewer nearby family members to disapprove, Riche, a Census Bureau director, said. 　　Just as in the US, those changes raised new questions about how involved government should be. in helping single parent families. Some research suggests children raised in two-parent families are better off than those who depend on one. "The position of one-parent families in any country is very much a gender (性别 ) issue -- women's opportunities, especially working-class women on low income," said Sue Cohen, coordinator ( 协调员) of the Single Action Parents Network in England~ (1) Not considering the exact number of the single-parent families, which country saw the fastest rise rate in 1999, compared with 19907 [　　] A． UK. B． Australia C． America D． Belgium. (2) What is the cause of the rise of single parent families across the globe? [　　] A． The nearby family members have a favourable opinion. B． A lone parent is well off enough lo support his/her children C． A lot of problems have arisen in two-parent families. D． We cannot get enough proving information from the text. (3) Which of the following is TRUE about the increase of single parent families according to the passage? [　　] A． It will somewhat limit the growing population of younger generation. B． Governments should take actions about the social problems brought about by it. C． Single parent families are not looked down upon in any country mentioned here. D． Generally speaking, the single parents needn't worry since they are. highly paid (4) Which of the following diagrams correctly shows the rise of single parent families in the US from 1990 to 2000? [　　] A． B． C． D．