:Read the text and choose the best answer to the questions

Ex6: Read the text and choose the best answer to the questions. (2 pts)
Tsunamis, whose name derives from the Japanese expression for “high wave in a harbor”, are giant sea waves. These waves are quite different from storm surges. They are also referred to by the general public as tidal waves although they have nothing to do with tides. Scientists often refer to them as seismic sea waves, which is far more appropriate because they are often the result of undersea seismic activity.
           Tsunamis can be caused when the sea floor suddenly moves, during an underwater earthquake or volcano, and the water above the moving earth is suddenly displaced. This sudden shift of water sets off a series of waves. These waves can travel great distances, at speeds close to 700 kilometers per hour. In the open ocean, tsunami waves are not very high, often no more than one or two meters. It is when they hit the shallow waters near the coast that they increase in height, possibly up to 40 meters.
1. The passage mainly discusses __________.         A. tidal waves    B. tides    C. tsunamis    
2. All of the following is true about tidal waves EXCEPT __________.
A. they are as another name for tsunamis.
B. they are caused by sudden changes in high and low tides.
C. this term is not used by the scientists.
3. The word “them” in the passage refers to _______.  A. tidal waves    B. tsunamis    C. storm surges
4. The word “shallow” in the passage mostly means _______.    A. not clear    B. tidal        C. not deep
5. It can be understood from the passage that tsunamis __________.
A. cause severe damage in the middle of the ocean
B. generally reach heights greater than 40 meters
C. are far more dangerous on the coast than in the open ocean