She had not slept for two days and was ______________.

Experiments are the most important part of __________ research.

The _________ of the Amazon rainforests is due to cutting of trees for construction and fires.

Loud noises make it difficult to _______ when you are studying.

They found a large, black ______ in a field.

There were only 96 _______ after the plane crashed.

An electron microscope can help you see the _________ parts of atoms.

Archeologists found the _______ of a dinosaur in the mountains.

It took her a week to ________ from the flu.

When asteroids ______ in space, the broken pieces of rocks sometimes fall to the earth.

The presence of ice on a _____ is ________ that it has water.

Hamad is studying the ______ of coral reefs, to learn about the plants and fish that live in the U.A.E coastline.

There are many ______ on the surface of the moon.

There are toxic levels of carbon dioxide in the _______ on Venus.