Question 9 is based on the passage you have just heard.

Passage One

听力原文

        Researchers have identified a potent new antibiotic compound using artificial intelligence. The antibiotic can kill very dangerous bacteria. According to a study published in the journal Cell, the compound successfully removed deadly strains of bacteria in mice which are resistant to all known antibiotics.

        (9) [The researchers say this is the first time that artificial intelligence has been used to find a powerful new antibiotic molecule.] Why does this matter? The answer is antibiotic resistance. This happens when bacteria develop the ability to survive the medications designed to kill them. (10) [Antibiotic resistance is a serious threat to health, and the problem is growing. This makes finding new antibiotics very important.] However, in recent decades, very few have been developed and those that have tend to be very similar to drugs already available. These searches also tend to only focus on a narrow spectrum of chemical compounds.

        But this is where artificial intelligence comes in. Why? To find new drugs, scientists screen molecules to predict how effective they might be. Typically, such screening is done by humans in the lab, which is both costly and slow. Artificial intelligence is different. It’s fast, and it can process a high volume. It can screen hundreds of millions of compounds to identify a few interesting candidates that require experimental testing.

        (11) [Artificial intelligence is also able to predict if compounds are likely to be toxic.] Some experts assert that this work signifies a paradigm shift in antibiotic discovery. It could change drug discovery more generally.

9. What have researchers done for the first time in history?（研究人员在历史上第一次做了什么？）

解析：A。录音开头提到，研究人员利用人工智能发现了一种有效的新型抗生素化合物，接着在后面又说这是人工智能首次（the first time）被用于寻找一种强大的新型抗生素分子。A项与此内容相符，其中的Utilizing对应录音中的used，artificial intelligence和find a powerful new antibiotic原词复现，因此A项为正确答案。

错项排除：B项利用录音中的resistant to all known antibiotics进行干扰，D项利用录音中的a new antibiotic和removed进行干扰，但录音中是说这种新型抗生素成功地消除了老鼠体内对所有已知抗生素都有耐药性的致命菌株，并不是发现了对所有已知抗生素都有耐药性的细菌，也不是消除了人体中的致命菌株，故B、D项均可排除。C项利用录音中的strains of bacteria进行干扰，但most harmful to human health在录音中无依据，故排除。