wget ( -roption) 的递归选项偶尔会产生很多文件。例如，wget -r www.cnn.com给出以下内容：
--2013-05-05 10:35:54-- http://www.cnn.com/about/
Reusing existing connection to www.cnn.com:80.
HTTP request sent, awaiting response... 200 OK
Length: unspecified [text/html]
Saving to: ‘www.cnn.com/about/index.html’
--2013-05-05 10:35:54-- http://www.cnn.com/help/
Reusing existing connection to www.cnn.com:80.
HTTP request sent, awaiting response... 200 OK
Length: unspecified [text/html]
Saving to: ‘www.cnn.com/help/index.html’
......
如何控制 - 我们可以指定下载的最大总大小、下载的最长时间等吗？