This is the VOA Special English Education Report.

And this is fifteen of our Foreign Student Series on higher education in the United States. Next week our subject will be the cost of attending an American college or university. But today we are going to stop and answer some more questions we have received.

The first one has to do with our recent discussion of admissions tests, including the Graduate Record Examination, or GRE.

Bhargavi Pottam writes from the American state of Pennsylvania to ask the difference between the GRE general test and subject tests. The GRE subject tests measure how much you know in an area like biochemistry, literature or mathematics. Graduate schools will tell you if they require one of these subject tests, or just the general test.

Marius Meledje from Ivory Coast wants to know if tests like the GRE and TOEFL must be taken before coming to the United States. In general the answer is yes.

After all, the tests must be taken before applying to colleges. So, unless you will be in the United States before starting your applications, you should take the tests in your home country.

Arnaud Kubwakristo from Rwanda asks how to begin applying to American graduate schools. And Bui Duc Kinh from Vietnam wants to know what kinds of tests they would require for a foreign student in environmental economics.

To answer the first question, our advice is to ask local professors which American schools have good programs in the area you want to study. Then go to the Web sites for those schools to find their requirements -- including the tests needed to apply.

Another listener from Vietnam, Loat Ngo, asks about recommendation letters -- why they are important and what they should contain. Letters written by teachers, employers and others can provide valuable information about you and your abilities and personality.

Schools may provide forms for you to give to the people who have agreed to write your recommendations.

You can get more information at sites like collegeboard.com or collegeview.com. Or just do an Internet search about letters of recommendation.

And that's the VOA Special English Education Report, written by Nancy Steinbach. For links to the Web sites for the GRE and other exams, and for the earlier reports in our series, go to voaspecialenglish.com.

To send us a general question that we might be able to answer on the air, write to special@voanews.com. Please be sure to include your name and country. I'm Steve Ember.