Color and luster are two ways to identify an unknown metal. Other ways include weight and composition.
'Climatic variations' and 'Human activities' can be regarded as the two main causes of desertification. removal of the natural vegetation cover（by taking too much fuel wood）, agricultural activities in the vulnerable ecosystems of arid and semi-arid areas, which are thus strained beyond their capacity.
What is the full question??
Answer:
Bad data in Geography causes a loss of accuracy in the size or position of objects on a map.
Earth was able to retain an atmosphere because of its gravity. It is <span>the same force that keeps us anchored to Earth. Molecules in our atmosphere are constantly moving, spurred on by energizing sunlight. If Earth were much less massive, gravity's grip would be weaker.</span>
