You can listen to part four of the science fiction story "A Princess of Mars" on our program AMERICAN STORIES this Saturday.

VOA: special.2010.07.28

The advantage of this is that now you have four binding sites for antigen instead of just two.

这样的好处是一个抗体上,有四个抗原结合位点而不仅仅是两个

耶鲁公开课 - 生物医学工程探索课程节选

It's just a little block of memory in RAM, you know, that represents four bytes, 32-bits and the Number Two is currently in it.

它只是一小块内存块，它表示4个字节，32位,那个数字2就存储在里面。

哈佛公开课 - 计算机科学课程节选

"All four of you took the decision not to proceed with terror training and all four of you realised what a shocking mistake you had made, " Mr Justice Henriques said as he sentenced them.

BBC: Terror plot: Jail terms for Birmingham bomb plotters

All you have to do is look at the coverage of Benghazi where you have four dead Americans, including the personal representative of the president of the United States, the US Ambassador, two former Navy Seals, and a long time foreign service officer.

CENTERFORSECURITYPOLICY: Monica Crowley, Mightier Pen 2012

"There were three attacks in the first 17 months of the administration, four if you count Fort Hood, " said Matthew Miller, who served as a director of the Office of Public Affairs for the Justice Department during Obama's first term.

CNN: Obama has learned tough lessons on using the word 'terror'