Oral route. Many drugs can be administered orally as liquids, capsules, tablets, or chewable tablets. Because the oral route is the most convenient and usually the safest and least expensive, it is the one most often used. However, it has limitations because of the way a drug typically moves through the digestive tract.
Measuring Distances to Stars. Astronomers use several techniques for discovering how far away an object is. The first is called trigonometric parallax and is based on geometry, but it is only good for up to about 500 light-years.
We know from experience how much light a car's headlights emits, so we can determine how far away the car is. To measure the distance to a galaxy, we try to find stars in that galaxy whose absolute light output we can measure. We can then determine how far away the galaxy is by observing the brightness of the stars.