So many people use the cell phones so frequently every day. But (1) little is certain about the health effects of its use. Manufacturers (2) that cell phones meet government standards for safe radio-frequency radiation emission, but enough studies are beginning to document a possible (3) in rare brain tumors (肿瘤), headaches and behavioral disorders in children to cause concern. So far, the evidence isn’t (4) on whether the use of cell phones (5) to any increased risk of cancer. In a new trial, researchers asked 47 volunteers to (6) in a project to measure glucose (葡萄糖) consumption in the brain by scanning the brain to see how cells use energy. For both 50-minute scans, the volunteers had a cell phone (7) to each ear. During the first scan, the devices were turned off, but for the second scan, the phone on the right ear was (8) on and received a recorded-message call, although the volum
So many people use the cell phones so frequently every day. But (1) little is certain about the health effects of its use. Manufacturers (2) that cell phones meet government standards for safe radio-frequency radiation emission, but enough studies are beginning to document a possible (3) in rare brain tumors (肿瘤), headaches and behavioral disorders in children to cause concern. So far, the evidence isn’t (4) on whether the use of cell phones (5) to any increased risk of cancer. In a new trial, researchers asked 47 volunteers to (6) in a project to measure glucose (葡萄糖) consumption in the brain by scanning the brain to see how cells use energy. For both 50-minute scans, the volunteers had a cell phone (7) to each ear. During the first scan, the devices were turned off, but for the second scan, the phone on the right ear was (8) on and received a recorded-message call, although the volum
Many people use wood stoves and fireplaces to heat their homes. Scientists have become worried about the smoke that they give off. Harmful chemicals are in the smoke. The smoke is causing air pollution. The pieces of pollution, called soot, are floating in the air. They are too tiny to see. Scientists must use a microscope to see them.
Small amounts of soot are safe, but large amounts can be dangerous. The government wants to limit this kind of pollution. It may stop people from using their fireplaces.
The air is tested every day. When soot levels are high, more than 65 micrograms of soot per cubic meter, factories must stop making smoke. The government thinks that limit should be much lower.
Factories produce the most smoke and soot. But the government thinks that all types of burning should be limited. The soot levels from factories and homes could be limited. Home owners may have to install new wood stoves that they comply with the new law. Or, they may
A. The fire could burn you.
B. It’s not healthy to be too warm.
C. Harmful chemicals are released in the soot.
D. The smoke is filled with unseeable tiny pieces.
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