Insect pests are among the leading causes of crop failure.
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The Salk vaccine is a major factor in the fight to eradicate polio.
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.
Withlasersscientistscanprobemanyphysicalprocesses,suchascombustion,oncebeyondourken.视野
Cream of tartar 酒石 , a weak acid, can be added to egg whites to help them foam泡沫 when they are beaten