题目

阅读理解 The ground we walk on seems firm, but deep under the earth and under the sea the rocks change and move. In some parts of the world there are “fire mountains”， which we call volcanoes. From time to time they burst open and throw out fire and burning ashes. These volcanoes are very dangerous. Hong Kong does not have any volcanoes but there are many volcanoes in Indonesia and Philippines. There is also a famous mountain near Tokyo, Japan, which is a volcano too. Its name is Mount Fuji. For much of the year，it is covered with snow. One of the most famous volcanoes which erupte屈肘时，肱二头肌和肱三头肌所处的状态是（ ）A．同时收缩 B．同时舒张C．肱二头肌收缩，肱三头肌舒张 D．肱二头肌舒张，肱三头肌收缩