The prefixes "con-" and "com-" are used with certain words to add the meaning "with" or "together", like "compound".combinecommercialcomparisoncompoundconcentrateconcernconsistentcontaincontextconvert1) He didn't seem ____ about his son's safety even if the boy hadn't come home.2) What rate will I get if I ____ my euros into US dollars?3) Our ____ effort and contribution will lead to the country's further development.4) The movie was not a ____ success because nearly 90% of the audience like it.

步骤 1：理解题意
题目要求使用前缀 "con-" 和 "com-" 来填空，这些前缀通常表示 "with" 或 "together" 的意思。我们需要根据每个句子的语境选择合适的单词。

步骤 2：分析句子
1) He didn't seem ____ about his son's safety even if the boy hadn't come home.
- 这里需要一个表示 "关心" 的词，因为前缀 "con-" 可以表示 "with"，所以 "concerned" 是合适的。
2) What rate will I get if I ____ my euros into US dollars?
- 这里需要一个表示 "转换" 的词，因为前缀 "con-" 可以表示 "together"，所以 "convert" 是合适的。
3) Our ____ effort and contribution will lead to the country's further development.
- 这里需要一个表示 "结合" 的词，因为前缀 "com-" 可以表示 "with"，所以 "combined" 是合适的。
4) The movie was not a ____ success because nearly 90% of the audience like it.
- 这里需要一个表示 "商业" 的词，因为前缀 "com-" 可以表示 "with"，所以 "commercial" 是合适的。

步骤 3：填写答案
根据上述分析，我们可以填写每个空格的答案。