But these factors do not account for the interesting question of how there came to be such a concentration of pregnant ichthyosaurs in a particular place very close to their time for giving birth.
In the seventeenth century the organ, the clavichord, and the harpsichord became the chief instruments of the keyboard group, a supremacy they maintained until the piano supplanted them at the end of the eighteenth century.
A series of mechanical improvements continuing well into nineteenth century, including the introduction of pedals to sustain tone or to soften it, the perfection of a metal frame and steel wire of the finest quality, finally produced an instrument capable of myriad tonal effects from the most delicate harmonies to an almost orchestral fullness of sound, from a liquid, singing tone to a sharp, percussive brilliance.
The largest later named pueblo bonito by the Spanish, rose in five terraced stories, contained more than 800 rooms, and could have housed a population of 1000 or more.
For a number of years the selection of music for each film program rested entirely in the hands of the conductor or leader of the orchestra, and very often the principal qualification for holding such position was not skill or taste so much as the ownership of large personal library of musical pieces. (not...so much as...与其说....不如说...)
The fact that half of the known species are thought to inhabit the word’s rain forest does not seem surprising, considering the huge numbers of insects that comprise the bulk of the species.
To appreciate fully the diversity and abundance of life in the sea, it helps to think small.(要充分认识海洋生命的多样性和丰富性，从小的角度思考有帮助）
Science is built with facts just as a house built with bricks, but a collection of facts cannot be called science any more than a pile of bricks ac be called a house.
The variation between the hemisphere corresponds to which side of the body is used to perform specific activities.
In a period characterized by the abandonment