单项选择题
A．he was doing some physical exercise B．that was the best way to keep balance C．the deck was uncomfortable to stand on D．he wanted to attract the watchers' attention
A．offered to help without knowing what to do B．did not want to put themselves in any danger C．realized the trouble but could do nothing about it D．did not know there was something wrong with the ship
A．the tide was not suitable B．she had run aground on sand C．her engines had broken down D．most of her crew had gone ashore