July 7, 1989

LEAD: AS you career headfirst down a 91-foot slope at 60 miles an hour, or whirl through a darkened, strobe-lighted dome, surrounded by ear-shattering disco music, or emerge from white-water rapids thoroughly drenched, you may be tempted to ask a very simple question: Why? More specifically, why travel miles, spend money and stand in line to subject yourself to such mad escapades?

LEAD: Attorney General Dick Thornburgh today conceded defeat at the hands of conservative Republican senators and abandoned his efforts to hire a prominent Manhattan lawyer, Robert B. Fiske, for the No. 2 post in the Justice Department.

LEAD: Striking a severe blow to New York City's efforts to prevent the spread of homelessness, the state's highest court ruled today that a city law prohibiting the conversion or demolition of single-room- occupancy housing is unconstitutional.

LEAD: In the three days since the United States Supreme Court handed down its ruling on abortion, New Jersey has become a stage for the next act of the nation's abortion conflict.

LEAD: Two of the nation's largest accounting firms announced merger plans yesterday, and two more confirmed that they were holding merger talks, as the already powerful firms sought greater international muscle to compete in serving multinational clients.

LEAD: Bush Selects Arts Official President Bush has selected John E. Frohnmayer, an Oregon lawyer, to head the National Endowment for the Arts. Page C3. New Cholesterol Estimate About 60 million Americans need to reduce cholesterol to cut heart disease risks, a new study says. Page A8. A Virtual Ban on Asbestos The Government will require a seven-year phase-out of nearly all remaining asbestos products.

LEAD: Housing Secretary Jack F. Kemp today suspended a program for the elderly that has already cost the Government $119 million in losses that cannot be recovered, the third troubled program he has shut down since he took office this year.

LEAD: The Supreme Court term that ended Monday was a watershed in the Court's modern history.

LEAD: Setting the stage for the seven-nation economic summit conference in Paris next week, President Bush said today that the United States would forgive some loans it has made to Africa's poorest countries.

LEAD: New York's highest court today expanded the legal definition of a family, holding that a gay couple who had lived together for a decade could be considered a family under New York City's rent-control regulations.

LEAD: FRIDAY BIG FISH IN A BIG POND

LEAD: President Mikhail S. Gorbachev today implicity renounced the use of force against other Soviet-bloc nations and offered to reduce Soviet short-range missiles ''without delay'' if NATO agreed to negotiations on such systems.