________把昭君嫁给了_________单于，为汉匈的友好相处和文化交流做出了重大贡献。
汉元帝；呼韩邪
The （） in e-mail messages has affected almost every computer around the world and has caused the damage of up to US$1 billion in North America.
A．illness
B．virus
C．weakness
D．attachment
下列元素属于沉积型循环的是（）。
A.碳
B.磷
C.氮
D.水
