What signs do scientists look for when predicting volcanic eruptions?

What evidence does the writer give to support his argument about coral reefs? a) he speaks of the activities of coral polyps. b) he describes the composition of the great barrier reef. c) he emphasizes the ways in which coral reefs are fragile. d) he points out the ways that scientists do research on the reefs.

How many time zone are there on earth

Which of the layers of the earth has the following three characteristics? i. it is a solid outer layer. ii. it is between 3 and 30 miles thick. iii. it is separated into plates. a. the outer core b. the inner core c. the mantle d. the crust