1. (2021高三上·上海月考) Directions: Read the passage carefully. Fill in each blank with a proper sentence given in the box. Each sentence can be used only once. Note that there are two more sentences than you need.

A. Besides, some scientists note that any new product like this will need to stand up to the real world, where dirt coats surfaces over time. B. It is calculated that covering a 1, 000-square-foot roof with this new paint could cool a building by about 10 kilowatts. C. The price of barium sulfate is comparable to, or even slightly more expensive than, titanium dioxide that is used in some other commercial paints. D. Now it's time to shed some light on the other end of the practical paint spectrum: the "whitest white." E. That is to say, this new paint can be a tool to fight the climate emergency by cutting carbon emissions. F. Unfortunately, manufacturing precise layers of multiple substances and applying them to a surface in a set order costs more than simply slapping on some paint.

Cool Colour

The "blackest black" paint, famed for its thermal disguise potential, has long absorbed 99.9 percent of public attention.  Research shows that surfaces coated with a newly formulated white coloring reflect 98. 1 percent of sunlight, creating a powerful cooling effect.

This coating absorbs just 1.9 percent of sunlight compared with 10 to 20 percent for conventional white or "heat-reflective" paints, says Xiulin Ruan, a Purdue University mechanical engineer. By reflecting so efficiently, the novel paint can actually help a coated building release the heat inside."Our model shows if you're in, you can save up to 70 to 80 percent on air-conditioning in the summer," Ruan says.

Scientists have been developing reflective paints for decades, but commercial products still remain at or above the surrounding temperature. In the past 10 years researchers have found greater success with multilayered coating to reflect many wave-lengths of light.

Thus, Ruan decided to take a hybrid approach and create an ordinary paint that could easily be brushed or sprayed onto a surface. After testing particles of several different compounds, he and his colleagues ultimately selected a relatively inexpensive one called barium sulfate.

Actually, there is plenty of competition from other researchers. The manufacturers have to struggle with "how to make sure that the paint stays white after 30 years of use." However, Ruan says he and his colleagues do have the confidence to remove this fear. He hopes to bring a version of his paint to market in a year or two.