In the face of earthquakes, science still has a lot to do. Through the study of seismic waves, people have found that seismic waves include longitudinal waves and shear waves. The former propagate faster, but the destructive force is smaller, while the latter is the opposite. Therefore, people use the earthquake monitoring network to monitor When the faster-propagating longitudinal wave of the seismic wave is transmitted, the monitoring center sends a signal to the monitoring center, and the monitoring center can use radio waves to send alerts to the public and key facilities through the client. In other words, the seismic alert is a "running race between radio waves and seismic transverse waves" "When the earthquake transverse wave has not yet arrived, warn people. What does this text mean? ['Difficulty in monitoring S-waves of seismic waves than P-waves.', 'The accuracy and speed of earthquake warning systems need to be improved.', 'The development of radio wave technology is a prerequisite for achieving pre-seismic prediction.', 'Scientific use of the time difference between two seismic waves can issue an effective earthquake alert.']