50. What does the author imply by saying aquaculture is no silver bullet?
- A. Shrimp-farming is a risky business.
- B. Fish-farming will not be sustainable.
- C. Fish-farming may cause serious problems too.
- D. Shrimp-farming can become quite expensive.
答案：C
答案句：However, aquaculture is no silver bullet. In some southeast Asian countries, shrimp farming does disastrous damage to marine ecosystems. Despite these problems, however, shrimp continues to be among the most popular sea foods worldwide.
参考译文：然而，水产养殖并非灵丹妙药。在一些东南亚国家，养虾对海洋生态系统造成了灾难性的破坏。尽管存在这些问题，虾仍然是全球最受欢迎的海鲜之一。
定位线索：题干“no silver bullet”→答案句“aquaculture is no silver bullet”和“shrimp farming does disastrous damage to marine ecosystems”；文中“does disastrous damage”对应选项C“may cause serious problems too”。
解析：题干问作者说“水产养殖并非灵丹妙药”暗示什么。“no silver bullet”意为“不是万能解决方案”，答案句随后举例说明养虾对海洋生态系统造成灾难性破坏，暗示水产养殖也可能带来严重问题。选项C“水产养殖也可能造成严重问题”是对此的合理推断。选项A“养虾是风险生意”范围过窄，选项B“水产养殖不可持续”程度过重，选项D“养虾会变得昂贵”在原文中未提及。