She called on Eritrea to clarify the whereabouts of 11 MPs who disappeared without a trace in September,2001.

VOA: standard.2009.04.09

I don't know how many know that there are trace, trace amounts, of cyanide in almonds.

我不知道有多少人知道在杏仁中有非常，非常微量的氰化物。

麻省理工公开课 - 化学原理课程节选

And I sent home a questionnaire, asking their parents because most of the children in the class come from other countries. In fact, just about everybody in America comes from another country if you trace far enough.

我还给家长们发了一张问卷，因为班上,大部分学生来自,其它国家，事实上，如果追根溯源，任何一个美国都来自,其它国家。

麻省理工公开课 - 媒体、教育、市场课程节选

Over the past few decades,however, scientists have determined that even trace amounts of lead in children's bodies leads to long-term neurological and behavioral problems.

VOA: standard.2009.12.19

"When the gas comes off the digester, it has not only methane in it it also has carbon dioxide And it has a trace of hydrogen sulfide."

VOA: standard.2010.02.23

At the same hearing, he says in one of the best studies used molecular fingerprinting to follow an outbreak of drug-resistant bacteria: "You actually can trace the specific bacteria around and they find that the resistant strains in humans match the resistant strains in the animals."

VOA: standard.2010.07.21