用放大镜观察物体时，应把物体放在（ ） A．焦距以内 B．一倍焦距与二倍焦距之间

常温下，下列各组离子能大量共存的是                               （  ）

A．含有HCO₃^－的澄清透明溶液中：K^＋、SiO₃^2－、Cl^－、Na^＋

B．pH＝0的溶液中：K⁺、Ba²⁺、Cl^－、HCO₃^－

C．水电离出的c(H⁺)·c(OH^－)＝10^－20的溶液中：Na⁺、ClO^－、S^2－、NH₄⁺

D．pH＝7的溶液：Fe³⁺、Mg²⁺、SO₄^2－、Cl^－

“三绿工程”是以哪三绿为主要内容？

《封神演义》中，传说由狐狸精变成的商纣王宠妃是谁？

提高思想意识、作风素质的关键是什么？

Originally introduced by Netscape Communications, (1) are a general mechanism which HTTP Server side applications, such as CGI (2) , can use to both store and retrieve information on the HTTP (2) side of the connection. Basically, Cookies can be used to compensate for the (4) nature of HTTP. The addition of a simple, persistent, client-side state significantly extends the capabilities of WWW-based (5) .

A. programs B. applications C. frameworks D. constrains