[单项选择]American scientists predicted that Mount Saint Helens was to erupt soon.

Can earthquake be predicted Scientists are (1) programs to predict where and when an earthquake will occur. They hope to (2) an early warning system that can be used to (3) earth-quakes so that lives can be saved. The scientists who are (4) this work is called seismologists. The word seismologist is (5) from the Greek word seismos, meaning earthquake.
Earthquakes are the most dangerous and (6) of all natural events. They occur in many parts of the world. Giant earthquakes have been (7) in Iran, China, India, Alaska, and so on. Two of the biggest earthquakes that were ever recorded (8) in China and Alaska, which measured about 8.5 on the Richter Scale. The Richter Scale was (9) by Charles Richter in 1935, and compares the energy (10) of earthquakes. An earthquake that measures a 2 on tile scale can be felt but causes (11) damage. One that measures 4.5 on the scale can cause slight damage, and an e
A. level
B. grade
C. strength
D. standard