For the third day in a row yesterday, the hallways of Winston Churchill High School were nearly silent during the normally bustling lunch period and the breaks between classes.The only sound that could be heard in one hallway was the whirring of a waxing machine a janitor was using on the floor.

And hundreds of desks were empty while students attended the funerals of two of their classmates at the school in Potomac, Louis Hannaway and Mary Carter Barrow, who were found dead early Sunday morning in a burning car. Both apparently had died of carbon monoxide poisoning before the fire.

"The whole school seems mesmerized," said Russell Reed, a student government leader. "Everybody seems to be talking in whispers."

The same atmosphere reigned in the classrooms, according to one teacher. "Hardly a word was spoken in 50 minutes of yearbook class on Monday," said Tom Timko, who teaches the class. "There's a real pall over the school."

School officials canceled two days of testing so students could go to the funerals.

The sudden and tragic deaths of Barrow and Hannaway have particularly gripped the school because the youngsters were so well known to their classmates.

Mary Carter Barrow, 16, a junior, was a member of the track team who hads participated in a several meets. She was described as the "spark" of the yearbook staff and was to become the president of the "Screaming Zonkers," the school's pep team.

Louis Hannaway, 17, a senior, and "always the guy who volunteered to stay late to do something," according to one classmate, was offensive right guard on the football team who started three games this school year and played on specialty teams.

"Most kids at Churchill (which has one of the highest academic ratings of any high school in Montgomery County) are very introverted. Carter and Louis were total extroverts," said Jim Stark, who composed a song for Mary Carter Barrow after her death and then sang it to the packed Faith United Methodist Church Tuesday at the girl's funeral service.

Just hours before their deaths, they had left friends at a surprise birthday party that both had spent almost all day Saturday helping to prepare.

It was, for many of those friends, their first experience of the death of someone close to them.

"It doesn't seem real to me yet. I don't know how it will affect my thinking about death," said Tracy Avenue, who lives across the street from the Barrows.

Much of the talk at the school concerns the various memorials the students have planned for Barrow and Hannaway. At the athletic field, two trees will be planted in their honor since both were involved in sports and both "were such a crucial part of our school spirit," said student Joe Callahan.

The youth group of the Faith United Methodist Church will paint a church meeting room yellow because sunshine yellow was Barrow's favorite color. At the school, many of the girl students carried around with them yellow flowers or wore them in their hair in honor of their friend.

"I can't tell you how many yellow rosebuds have been handed to me over the past few days," said Peggy Barrow, mother of the dead girl.

The depth of their (the students') understanding and what they felt for Carter has been immeasurable to us," Mrs. Barrow said.

Both youngsters were described most frequently by their friends as "always smiling," and "happy-go-lucky."

According to friends, Carter Barrow left the birthday party after midnight because she was feeling tired and ill. She had run in a two-mild relay the day before. Louis Hannaway drove her to his own home, at 10609 Gainsborough Rd., Potomac, then returned to the party.

About 1 a.m., according to police, Hannaway returned home to drive Barrow to her home at 8107 Postoak Dr., also in Potomac, with another girl. He dropped the second girl off, but then - for reasons that the police, the parents and friends of the dead girl cannot piece together - he parked the car around the corner from the Barrow home and apparently kept the engine running.

About 3 a.m., passersby spotted the car in flames and alerted a neighbor who called the fire department. Hannaway was found on the front seat and Barrow in the back, covered by a blanket. Police said a preliminary autopsy showed the youths died of carbon monoxide poisoning, and suicide and foul play were ruled out. The cause of the fire still under investigation.

The song written by their classmate, Jim Stark, for Carter Barrow attempted to express what he said he and the others were feeling: