Oft the teeming浇铸 earth① Is with kind of colic pinch''d挤压 and vex'd'd烦恼 By the imprisoning of unruly wind Within her womb发源地; which for enlargement striving抗争 Shakes the old bedlam疯人院 earth and topples down Steeples教堂尖塔 and moss-grown

Atomic Structure All natural and most synthetic substances on earth are made from the ninety naturally occurring chemical elements. An atom is the smallest particle into which an element can be divided while still retaining the chemical characteristics of that element (fig 3. 1). The nucleus, at the center of the atom contains one or more particles with a positive electrical charge(protons fif and usually some particles of similar mass that have no charge(neutrons

1、早期的太阳系 The Early Solar System Billions of years ago, out of a swirling mass of gas and dust, evolved a system of varied planets hurtling around a nuclear-powered star-our solar system. One of these planets, and one only, give rise to complex life forms. Over time