function createhttp_request(){
http_request = false;
if(window.XMLHttpRequest) {
http_request = new XMLHttpRequest();
if (http_request.overrideMimeType) {
http_request.overrideMimeType('text/xml');
}
}
else if (window.ActiveXObject) {
try {
http_request = new ActiveXObject("Msxml2.XMLHTTP");
} catch (e) {
try {
http_request = new ActiveXObject("Microsoft.XMLHTTP");
} catch (e) {}
}
}
if (!http_reques

基础知识目标主要是依据课后的有关训练题设计的。用词达意的训练主要是在理解的基础上注意积累和运用，句子的训练是抓关键词语理解句意。