How many rooftop solar water heaters are there in China currently? How many Chinese companies are manufacturing devices
举一反三
- Currently there are 1 rooftop solar water heaters in China. Nearly 2 Chinese companies are manufacturing these devices.
- Currently there are ______ rooftop solar water heaters in China.
- Why is it so rare to see rooftop solar water heaters in America while such devices are commonplace in China?
- The rooftop solar water heaters provide ______ without consuming any fuel.
- How many solar terms are there in each season?