By now, you must have learned how to use "a/am" and "the" properly.
It may seem confusing but once you learn the basic concpet and remember commonly used phrases, you'll be OK.
Just pay attention whenever you read or hear "a/an" or "the".
 Listening: Open Forum Chapter 11 Math and Technology #4
Review: A Lecture about human computers/p.92-93 #1 Listen w/Script
- Pronunciation; The -ed Ending
- Speaking Skills
Web Listening: A Tour Guide Talk about a Museum of Science and Technology
- Lis #1: Answer the Questions
- Lis #2: 1. What is BBC? 2. What could BBC Model-B do?
=> Summarize what you learned in the tour. Grammar: Grammar in Use
- Review Unit 72: a/an and the - 72-A-> 72.1, 72-B-> 72.2, 72-C-> 72.3
- Unit 73: The 1 - 73-A, B-> 73.1, 73-C-> 73.2, 73-D-> 73.3-> 73-E-> 73.4