Marilyn Flook, a medium-built woman with long brown hair, sat at the dining room table, her fingers carefully striking the edges of a coffee cup. "I'm trying to start my life all over," she said softly. "But how do you do that when you've lost someone you love?"

It has been 46 days since her husband, Frank, was gunned down by one of two men who tried to force their way into the couple's town house.

"It's [the memory of the murder] always there," she said yesterday."Some days more than others. Especially during those times of the day that we spent together. There are things that bring it to mind. The ringing of the doorbell is the worst thing for me whether I'm at home or at someone else's house."

It was the constant ringing of the doorbell that awakened Marilyn Flook on the night of Dec. 27. The ringing had become so irritating that she went downstairs to see who was at the door.

She mistook a male figure outside to be the paper boy. When she opened the door, two men began pushing it from the outside. As she struggled to get the door closed, her husband of 3 1/2 years rushed to help. He was shot by one of two men who fled, taking nothing.

Frank Flook, who died at 33, was one of several victims of seemingly random killings that have occurred in the city over the past two months.

A day before Flook was killed, Gerald Adler, a 66-year-old Gallaudet College professor, was fatally shot during a robbery in the parking garage of his Southwest Washington apartment building.

Carl K. Lane, the 63-year-old proprietor of a haberdashery, was fatally shot in the head in the parking lot beside his shop at 3608 Georgia Ave. NW, on Jan. 14.

Three days later, 35-year-old Matilda Nesbitt was killed during a robbery in the 800 block of L Street NE., where she was walking toward a bus stop after leaving a church bingo game.

All these murders also are unsolved.

Through the help of friends and neighbors, Flook said, she is gradually pulling her life together. "I try to stay busy. My friends have been good. They keep me busy and make sure that I am not alone."

Within an hour the other evening, she received six telephone calls from friends checking up on her. One co-worker invited her to join friends for pizza and beer. Another call was to invite her to dinner for the next evening.

"I have more invitations than I can handle," she said. "Everyone is so nice. And just to think when we moved here (in July from Jacksonville, Fla.) we only had one friend who we knew . . .

Flook, 32, has learned to stay busy. Last weekend, she wallpapered her kitchen. "I try not to come home without having something planned. that way I don't get so depressed . . . But there are times that I just want to be by myself. But I'm trying not to do that too much. You can easily slip into depression that way."

Two weeks ago, she returned to her job as a planning and development representative for the Washington area office of the U. S. Department of Housing and Urban Development.

She said questions linger about the slaying. "Why us? That'st always on my mind. Did someone have something against Frank? Was it the house? Anybody familiar with Capitol Hill prices knows that you spend all your money trying to make the mortgage."

"Who would want an old black and white portable TV anyway?" she said, looking at the set on the dining room table. "We don't have any valuables. We don't keep any money in the house. Why us?

"When they arrest somebody, maybe I'll find the answer then," she said. "But I may never find the answer. Then again, is it really that important? Is it best to forget it? After all, I'm trying to start my life over."

Flook said she has not decided how long she will stay in the two-story turn-of-the-century town house that she and her husband moved into last August. "What to do about the house is weighing on my mind," she said.

"It's a big house," she said, patting her cat, Charmin. "It's lonely . . . but then I will be lonely wherever I live."

Her neighbors hope she will stay, but, like her friends, they agree that the decision is hers.

Some of the neighbors have chipped in for a $1,000 reward for information leading to the arrest of Flook's slayer. District of Columbia police say they have some leads in the case.

The Flooks were the only white couple on the block of 21 two-story mostly owner-occupied homes in the predominantly black neighborhood. The house is renovated and with its bright green and yellow colors stands out among the red brick homes.

The incident has upset the normally quiet block -- the 1500 block of A Street NE -- one of several honored in the mid-60s under Lady Bird Johnson's beautification program.

"It (the shooting) was uncalled for," said Ella Blakeney, who has lived on the block since 1955. "They were very nice neighbors."

Blakeney, like many of Flook's neighbors, had never visited the couple's home, but often had said hello to them.

"Everytime I look over there, I get sick," said Thelma Samuels, who has lived on the block for 23 years. "I hope she will be all right."

"Everybody is wondering who did it," said another neighbor. "It scares you. You don't know whether it was somebody here in the neighborhood or from far away. Everybody is a little nervous."

Some neighbors said they have become more cautious about opening their doors to strangers. One neighbor has begun leaving her back yard floodlight on all night. Others are curtailing their activity at night.

"Nobody is getting out like they used to," said Edna Benson, who has been on the block for 20 years.

And said Rita Yates: "Nobody will every be the same until these people are caught."