And now is the time for all of us to take our share of responsibility for a global response to global challenges."

VOA: standard.2009.09.23

The challenges that... First of all, you got to understand that learning a language takes time.

挑战就是，首先，你必须明白学习一门语言是件耗时间的事。

学第二外语的时候 - SpeakingMax英语口语达人

"Climate change challenges us all to find a new development paradigm that balances economic growth and long-term prosperity with social progress and ecological sustainability.

VOA: standard.2009.09.01

"And that is why I will accept this award as a call to action, a call for all nations to confront the common challenges of the 21st century,"

VOA: standard.2009.12.10

"And that is why I will accept this award - as a call to action, a call for all nations to confront the common challenges of the 21st century,"

VOA: standard.2009.12.10

But with inflation and all of the economic challenges that have taken place in the world, the allowances that were given to teachers for working in the remote areas have now become ridiculously low."

VOA: standard.2010.02.25

When it was his turn to speak, Mr.Obama said old grievances in the hemisphere should be set aside, replaced by a renewed commitment to expand prosperity, security and freedom in the Americas, with all nations working as equals to confront common challenges.

VOA: standard.2009.04.17

And without a vaccine, Dr.Fauci says the best methods of prevention are these: encourage people to limit the numbers of sexual partners encourage men to use condoms train more doctors to perform adult male circumcision empower women to choose their sex partners and protect themselves from getting the virus that causes AIDS All of these goals still remain major challenges.

VOA: standard.2010.07.17