The word “precious” in the passage is closest in meaning to
Exact b. scare c. valuable d.initial
Although limited to a skull, the Pakicetus fossil provides precious details on the origins of ……
The word “exposed” in the passage is closest in mening to
Explained b. visible c.identified d. located
Several skeletons of another early whale, Basilosaurus, were found in sediments left by…and now exposed in the Sahara desert.
The word “propulsion” in the passage is closest in meaning to
Staying afloat b.changing direction c. decreasing weight d.moving forward
The structure of the backbone shows, however, that it swam like modern whales by moving the rear portion of its body up and down, even though a fluke was missing. The large hind legs were used for propulsion in water.
The word “threatened” in the passage is cloest in mening to
Restricted b. endangered c. prevented d. rejected
The expansion of desert-like conditions into areas where they did not previously exist is called deserfication. It has been estimated that an additional one-fourth of the Earth’s land surface is threatened by this process.
The word “delicate” in the passage is cloest in meaning to
Fragile b.predictable c. complex d.valuable
The semiarid lands bordering the deserts exist in a delicate ecological balance and are limited in their potential to adjust to increased exvironmental pressures.
The word “progressively” in the passage is cloest in meaning to
Openly b. impressively c. objectively d.increasingly
The cultivation of crops has expanded into progressively drier regions as population densities have grown.
The phrase “devoid of” in the passage is closest in meaning to
Consisting of b. hidden by c. except for d. lacking in
Since the raising of most crops necessitates the prior removal of the natural vegetation, crop failures leave extensive tra