Fill in the blanks with an appropriate verb form.

Water …………………….. (cover / covers / is covering) most of the Earth. ………………………. (compared / comparing / having compared) to forests, prairies, and other ecosystems, the deep sea is by far the largest ecosystem on the planet. So, if you want to understand Planet Earth, you have to understand its oceans.

A team of researchers recently ……………………… (made / had made / were making) an 11-day expedition to the Bahamas to do just that. The expedition, called Deep Scope 2007, ……………………… (used / were using / have used) a tank like submersible to drop off and pick up a special camera system called the Eye-in-the-Sea, or EITS. The camera ……………………………. (is filming / films / has filmed) with red light, which most deep-sea animals can’t see, so they …………………………. (don’t get / won’t get / didn’t get) scared away.

One of the biggest advantages of EITS is that it ………………………… (allow / allows / is allowing) researchers to see how deep-sea creatures communicate with one another—using a type of light called bioluminescence. Bioluminescent creatures ………………………. (use / are using / have used) chemicals to make their own light. Scientists believe that sea creatures use this light for everything from ………………………… (scare / scaring / scared) away predators to finding food in dark waters.

Answers

Water covers most of the Earth. Compared to forests, prairies, and other ecosystems, the deep sea is by far the largest ecosystem on the planet. So, if you want to understand Planet Earth, you have to understand its oceans.

A team of researchers recently made an 11-day expedition to the Bahamas to do just that. The expedition, called Deep Scope 2007, used a tank like submersible to drop off and pick up a special camera system called the Eye-in-the-Sea, or EITS. The camera films with red light, which most deep-sea animals can’t see, so they don’t get scared away.

One of the biggest advantages of EITS is that it allows researchers to see how deep-sea creatures communicate with one another—using a type of light called bioluminescence. Bioluminescent creatures use chemicals to make their own light. Scientists believe that sea creatures use this light for everything from scaring away predators to finding food in dark waters.