单项选择题
A．for entertainment and relaxation B．to work out complex problems C．to do any of the ten things mentioned in the reading D．to keep track of expenses and turn appliances on and off
A．used to be too small to use B．used to be nice C．used to be heavy D．used to be large and expensive
A．because the Americans want to appear rich B．because they are smaller, cheaper and easier to use C．because they can help Americans do everything D．because 'they can type letters