The boy sat down on a stone to take a pebble out of his shoe when he saw a stranger approaching him.
A. 小男孩在石头上坐下来正要从鞋里取出小石子,这时他看见一个陌生人朝着他走来.
B. 当他看见一个奇怪的人靠拢他时,小男孩正坐在石头上,把小石子从鞋里取出来.
C. 当小男孩坐在石头上,从鞋里取出小石子,接着他看见一个古怪的人正朝着他走来.
D. 当小男孩坐在石头上从鞋里取出小石子时,他看见一个陌生人正朝他走来.