单项选择题
A．ahead one hour in each new time zone B．ahead one hour for the whole trip C．back one hour in each new time zone D．back one hour for the whole trip
A．as B．for C．to D．at
A．burning fossil fuels to make electricity is widely used B．wind power is a widespread way to make electricity C．energy problems will soon be solved D．nuclear energy will solve all the energy problems we are facing