读“某河流域示意图”完成1—2题。

1、图中河流的甲——乙河段流域范围非常狭窄，其主要原因是 [ ]

A、泥沙淤积使河床过高，支流难以汇入

B、河流两岸被高山束缚，山高谷深

C、上游气候寒冷干燥，支流稀少

D、河流落差大，水流湍急

2、该河流中、下游平原是重要农业区，影响其农业生产的优势社会经济条件是

    ①人口稠密，劳动力充足 ②水、陆交通发达，便于粮食大量出口

    ③历史悠久，种植经验丰富 ④地广人稀，土地租金低

    ⑤科技发达，机械化水平高 ⑥人多地少，粮食需求大量 [ ]

A、①②④

B、①③⑥

C、②④⑤

D、③⑤⑥

Pharming is a scamming practice in which malicious code is installed on a personal computer or server,misdirecting users to ______ Web sites without their knowledge or consent. Pharming has been called "phishingwithout a lure".
In phishing, the perpetrator sends out legitimate-______ e-mails, appearing to come from some of theWeb’s most popular sites, in an effort to obtain personal and financial information from individualrecipients. But in pharming, larger numbers of computer users can be ______ because it is not necessaryto target individuals one by one and no conscious action is required on the part of the victim. In one form ofpharming attack, code sent in an e-mail modifies local host files on a personal computer. The host filesconvert URLs into the number strings that the computer uses to access Web sites. A computer with acompromised host file will go to the fake Web site even if a user types in the correct Internet address orclicks on an affected ______ entry. Some spyware removal programs can correct the corruption, but itfrequently recurs unless the user changes browsing ______

A. hypertext B. computationC. expectationD. bookmark