21. There are many volcanoes ________.
A. everywhere in the world B. under the earth and the sea
C. in Hong Kong D. in Indonesia
22. The people near Krakatoa were unprepared when it had its biggest explosions because people there ________.
A. had never met any explosions of the volcano before
B. were used to the explosions by that time
C. didn't want to leave their island
D. could do nothing but wait
