A Valuable Discovery

Words in Use (Lesson 16)

• slender
• surpass
• vast
• doubt
• capacity
• penetrate
• pierce
• accurate
• microscope
• grateful
• cautious
• confident

Read the following passage to see how the new words are used in it.
  
A Valuable Discovery
The laser is a marvelous device that sends out a slender, concentrated beam of light, a light that surpasses the light at the sun's surface. So vast is the laser beam's power that it has without a doubt the capacity to vaporize* any substance located anywhere on earth. The laser can penetrate steel, pierce a diamond, or make an accurate die for wire so thin that it can be seen only with a microscope. Grateful eye surgeons report that they have used laser beams to repair the retinas in some fortunate* patients by creating tiny scars that joined the retina to the eyeball. Pioneering* medical men are making cautious exploration* into cancer cures with the laser, confident that they will alter* the course of this brutal* disease.