(21) summary of the physical and chemical (22) of life must begin, not on the Earth, but (23) the Sun; in fact, (24) the Sun’s very center. (25) is here that is to be found the (26) of the energy that the Sun constantly (27) space (28) light and heat. This energy is liberated at the center of the Sun as billions upon billions of nuclei hydrogen atoms (29) each other and (30) to form nuclei of helium, and, (31) doing so, (32) some of the energy that is stored in the nuclei of atoms. The output of light and heat of the Sun (33) that some 600 million tons of hydrogen (34) helium in the Sun every second. This the Sun (35) for several thousands of millions of years.
(21)() A summary of the physical and chemical
nature of life must begin, not on the Earth, but in the Sun; in {{U}} (67)
{{/U}} at the Sun’s very center. It is here that is to be found the
{{U}} (68) {{/U}} of the energy that the Sun pours out into space is
{{U}} (69) {{/U}} The energy takes the form of light and heat. This
energy is {{U}} (70) {{/U}} at the center of the Sun as billions
{{U}} (71) {{/U}} billions of nuclei of hydrogen atoms {{U}} (72)
{{/U}} with each other and fuse together to form nuclei of helium, and in
doing so, {{U}} (73) {{/U}} some of the energy that is {{U}} (74)
{{/U}} in the nuclei of atoms. The {{U}} (75) {{/U}} of light and
heat of the Sun {{U}} (76) {{/U}} that some 600 million tons of hydrogen
be {{U}} (77) {{/U}} into helium (氦) in the Sun every second. This the
Sun has been doing for several thousands of mil A. nature B. fact C. research D. addition 我来回答: 提交
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