单项选择题
A. At home. B. In an office. C. In a taxi.
A. Some animals and plants depend on each other for existence. B. Some animals and plants develop their relationship easily. C. Some plants depend on each other for food. D. Some animals live better together.
A. you are patient B. you obey all the traffic rules C. you don’t cut another car off D. you wait in line at a red light