确认大肠杆菌来源仍是一挑战

短语讲解：

1. U.S. health experts say tracking down a deadly germ can be a complicated task.

track down找到，发现；查出
例句：They hope to track down the source of the infection .
他们希望查出这种传染病的根源。

2. When they notice an unusual number of people coming down with food poisoning, the first thing public health officials do is try to find out what they all ate recently.

come down患病, 病倒
例句：He came down with pneumonia last week.
上星期, 他得肺炎病倒了。
find out发现, 看穿, 揭发, 找出;查明
例句：We must find out the truth of the matter.
我们必须弄清楚事情的真相。

3. And even if they do, they may not know all the ingredients, or where they came from.

even if即使, 纵然
例句：I wouldn't lose courage even if I should fail ten times.
即使要失败十次, 我也绝不灰心。

4. For example, he says, a tomato condiment called salsa was one of the suspects in a 2008 Salmonella outbreak in the United States.

for example　例如, 譬如
例句：I know many women who have a career and a family—Kehr for example.
我知道有许多妇女能事业家庭兼顾——凯尔就是其中之一。

5. Tracing the germ all the way back to the grower may help investigators figure out what went wrong and how to keep it from happening again.

figure out弄明白，理解; 想出
例句：We must figure out how to do it.
我们必须想出做这件事的办法。
keep from阻止; 免于
例句：Urgent business kept me from attending the meeting.
因有急事我不能去参加会议。

6. He notes that investigators have been focusing on fresh produce, but at this point, weeks after the outbreak started, they may not even be able to trace the offending item as far as the patient's refrigerator.

focus on致力于, 集中于
例句：He focused his mind on his lessons.
他把心思集中在功课上。

7. The U.S. state of Oregon's public health department is recognized as one of the nation's best. But sometimes officials there are stumped.

be recognized as被公认为…
例句：His works are recognized as the most excellent in that period
他的作品被认为是那个时代最优秀的作品。

8. There have been a couple where there's been, really, at the end of the day, no idea what the product was.

at the end of在…结尾,在…末端
例句：The audience clapped at the end of the play.
剧终时观众鼓掌。

9. Meanwhile, European officials say the number of new E. coli cases appears to be slowing down.

slow down减速; 慢下来
例句：Business slows down in summer.
夏季生意清淡。

10. That may mean the outbreak will soon come to an end, with or without identifying the cause.

come to an end结束,终止
例句：All good things must come to an end.
天下无不散之筵席。