36.Most striking among the many asymmetries evident in an adult flatfish is eye placement: before maturity one eye migrates,so that in an adult flatfish both eyes are on the same side of the head. 来源:考试大
37.The best evidence for the layered-mantle thesis is the well-established fact that volcanic rocks found on oceanic islands,islands believed to result from mantle plumes arising from the lower mantle,are composed of material fundamentally different from that of the midocean ridge system, whose source,most geologists contend,is the upper mantle.
38.Some geologists,however,on the basis of observations concerning mantle xenoliths, argue that the mantle is not layered,but that heterogeneity is created by fluids rich in "incompatible elements" (elements tending toward liquid rather than solid state)percolating upward and transforming portions of the upper mantle irregularly,according to the vagaries of the fluids’ pathways. 来源:考试大
39.The very richness and complexity of the meaningful relationships that kept presenting and rearranging themselves on all levels,from abstract intelligence to profound dreamy feelings, made it difficult for Proust to set them out coherently. 来源:考试大
40.It is possible to make specific complementary DNA’s (cDNA’s)that can serve as molecular probes to seek out the messenger RNA’s (mRNA’s)of the peptide hormones. If brain cells are making the hormones,the cells will contain these Mrna’S. If the products the brain cells make resemble the hormones but are not identical to them,then the cDNA’s should still bind to these mRNA’s,but should not bind as tightly as they would to mRNA’s for the true hormones.