单项选择题
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．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．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