单项选择题
A．The bikes were more expensive than it is today. B．People’s salary was very low. C．Most people could afford a bike. D．People lived in courtyard houses with very good equipment.
A．for children to take advantage of their parents by using a foreign language B．to expose children to a foreign language after they can speak English C．to combine language lessons with sports games D．for children to learn several languages at the same time
A．alert themselves to the approaching enemy B．emerge from water now and then to breathe C．be sensitive to the ever-changing environment D．avoid being swept away by rapid currents