It has been a hundred years since the last big one in California, the 1906 San Francisco e

arth quake, which helped give (1)_____ to modem earthquake science. A century later, we have a highly successful (2)_____, called plate tectonics, that explains why 1906-type earthquakes happen—along with why continents drift, mountains rise, and volcanoes (3)_____ the Pacific Rim. Plate tectonics may be one of the (4)_____ triumphs of the human mind, geology's (5)_____ to biology's theory of evolution. And yet scientists still can't say when an earthquake will happen. They can't even come (6)_____.

What scientists can do right now is make good maps of fault zones and (7)_____ out which ones are probably due (8)_____ a rupture. And they can make forecasts. A forecast might say that, over a certain number of years, there is a certain (9)_____ of a certain magnitude earthquake in a (10)_____ spot. And that you should fix your house to its foundation and glue the water heater to the wall.

Turning forecasts into predictions—"a magnitude 7 earthquake is (11)_____ here three days from now"—may be impossible, but scientists are doing everything they can to solve the (12)_____ of earth quakes. They break rocks in laboratories, studying how stone (13)_____ under stress. They hike (14)_____ ghost forests where dead trees (15)_____ of long-ago tsunamis. They make maps of unsecured, balanced rocks to see where the ground has (16)_____ in the past and how hard. They dig ditches across faults, searching for the active trace. They have wired up fault zones with so many sensors it is (17)_____ the Earth is a patient (18)_____ intensive care.

(19)_____, we tell ourselves—trying hard to be persuasive—there must be some way to (20)_____ order and criterion on all that untrustworthy ground.

A．birth

B．rise

C．ground

D．way