Tritium is one of the mildest radioactive isotopes.氚是最和缓的放射性同位素之一.More reactive are the heavier isotopes of hydrogen, deuterium and tritium.更为活跃的是氢的较重同位素, 氘和氚.Tritium has a half - life of 12.4 years.氚的半衰期为12.4年,地球形成时的氚早已...
After the Norman Conquest the forest became a royal hunting preserve.诺曼征服之后，这片森林成为了皇家狩猎区。Norman cut open his pie and squirted tomato sauce into it.诺尔曼切开自己的派，往里面挤了点番茄酱。It is located within reach of many important Norman t...