答案：C

翻译：洪灾的早期警报，在广播电视上广播以后，迅速传遍了这个地区。

解释：

1. to be done即不定式的被动结构做后置定语时，表示不定式所含动词所表示的动作在谓语动词发生时尚未发生。

如：The meeting to be held tomorrow is about the sports meeting..

明天将要举行的会议是关于校运会的。

2. 根据此题句意，broadcast over the radio and on TV该动作明显发生在谓语动词spread...之前，而并不是当时尚未发生，所以不能选D。

3. A项不能做后置定语，而B表示the early warning of floods和broadcast之间为主动关系且broadcast动作当时正在进行，不符合句意，均排除。

4. 过去分词做后置定语时，不但表示其动作已经发生，而且表示被修饰成分和该动词之间为被动关系，所以答案C为正解。

Facial expressions carry meaning that is determined by situations and relationships. For example, in American culture the smile is in general an expression of pleasure. Yet it also has other uses. A woman's smile at a police officer does not carry the same meaning as the smile she gives to a young child. A smile may show love or politeness. It can also hide true feelings. It often causes confusion across cultures. For example, many people in Russia smiling at strangers in public to be unusual and even improper. Yet many Americans smile freely at strangers in public places (although this is less common in big cities). Some Russians believe that Americans smile in the wrong places; some Americans believe that Russians don't smile enough. In Southeast Asian culture, a smile is frequently used to cover painful feelings. Vietnamese people may tell a sad story but end the story with a smile.

面部表情的含义由场合和关系决定。例如，在美国文化中微笑通常是一种快乐的表达，不过也有其他含义，女人对警察微笑与她对小孩的微笑含义不同。微笑可以表示爱或礼貌，也可以隐藏真实的感情。它经常引起跨文化的困惑。例如，在俄罗斯，许多人当众对陌生人微笑是不寻常的，甚至是不恰当的。然而，许多美国人在公共场所对陌生人随意微笑（尽管在大城市并不常见）。一些俄罗斯人认为美国人微笑的场合不当；一些美国人认为俄罗斯人笑得不够。在东南亚文化中，微笑经常被用来掩饰痛苦的感觉。越南人可能会讲一个悲伤的故事，但以微笑结束故事。

Our faces show emotions, but we should not attempt to "read" people from another culture as we would "read" someone from our own culture. The fact that members of one culture do not express their emotions as openly as do members of another does not mean that they do not experience emotions. Rather, there are cultural differences in the amount of facial expressions permitted. For example, in public and in formal situations many Japanese do not show their emotions as freely as Americans do. When with friends, Japanese and Americans seem to show their emotions similarly.

我们的脸上流露出情感，但我们不应该像“阅读”来自我们自己文化的人一样，试图“阅读”来自另一种文化的人。事实上一种文化的成员不像另一种文化的成员那样公开表达自己的情感，并不意味着他们没有经历情感。相反，在允许的面部表情数量上存在文化差异。例如，在公开场合和正式场合，许多日本人不像美国人那样自由地表达自己的情感，而和朋友在一起时，日本人和美国人似乎表现出相似的情感。

It is difficult to generalize about Americans and facial expressiveness because of personal and cultural differences in the United States. People from certain cultural backgrounds in the United States seem to be more facially expressive than others. The key is to try not to judge people whose ways of showing emotion are different. If we judge according to our own cultural habits, we may make the mistake of "reading" the other person incorrectly.

由于美国的个人和文化差异，很难对美国人和面部表情进行概括。在美国，来自某些文化背景的人似乎比其他人更善于表达自己的观点，关键是不要评判那些表达情感方式不同的人。如果我们根据自己的文化习惯来判断，我们可能会犯错误地“阅读”他人。