About 60 percent of all known galaxies are classified as

a. spiral galaxies
b. elliptical galaxies
c. irregular galaxies
d. binary systems

In the water cycle , when does water undergo a chemical change

The pressurized plants and fungi mentioned in the video have some surprising similarities. what differences would you expect them to have?

Which statements explains what the fossil records indicates? check all that apply. a) earth is 4.5 billion years old b) many organisms have become extinct c) mammals have always existed on earth d) mass extinctions have occurred several times on earth e) the amount of water on earth has decreased over time?