When carbon is added to iron in the proper proportions , the result is steel.

Some children display an unquenchable 难以抑制的 curiosity about every new thing they encounter.

The megaphone(microphone) makes the voice sound louder because it points sound waves in one direction and keeps them from spreading out in all directions.

Formerly , in the United States, many nurses worked as private duty nurses rather than in hospitals.

Alligatorsstillexistinsomeofthedank潮湿swampsandbayous小海湾ofAlabama'scoastalregions.