Which is an effective way scientists study ancient climates?

a, read very old books

b. review old maps

c. drill deep into glaciers

d. study other planets

Which objects allow humans to access groundwater? check all that apply.

[ou.01jthe greatest speed with which any physical object moves is 300,000 km/soundsec. which of the following has a speed of 300,000 km/sec? a.light in water b.light in vacuum c.sound in air. d. sound in water

Which of teh following would explain the importance of the trans-siberian railroad to russia's economy? (schoology test)