[单选题][单选题]血细胞比容在正常成人约为
A.6％~8％
B.20％~30％
C.40％~50％
D.60%
E.70％~80％

{{B}}Save Energy at Home{{/B}}
On the average, Americans waste as much energy as two-thirds of the world’s population consumes. That’s{{U}} (1) {{/U}}the result of driving inefficient cars, using inefficient appliances, and living and working in poorly insulated buildings. Then what can you do to improve the{{U}} (2) {{/U}}
Buy energy-efficient products.—Buy new appliances or electronics of the highest energy efficiency rating. New energy efficient models may cost more initially, but have a lower operating{{U}} (3) {{/U}}over their lifetimes. The most energy-efficient models{{U}} (4) {{/U}}the Energy Star label, which identifies products that use 20-40 per cent less energy than standard new products. According to the EPA, the typical American household can save about $-400 per year in{{U}} (5) {{/U}}bills with products that carry the Energy Sta
A. phone
B. water
C. food
D. energy