the many isotopes of carbon碳的诸多同位素Tritium is one of the mildest radioactive isotopes.氚是最和缓的放射性同位素之一.The inferno spewed a deadly plume of radioactive isotopes into the atmosphere.这个象炼狱般的地方将一缕致死的放射性同位素喷入大气层....
The feather must be removed with a straight, firm pull.拔羽毛必须干净利落。I taped the base of the feather onto the velvet.我用胶带把羽毛的根部粘在了天鹅绒上。Harry'sappointment to this important post was a feather in his cap.哈里被任命担任如此要职，这是件荣耀...
从外表上看, 她又很迷人 、 又肯助人.On the surface, she's a charming, helpful person.现在流行的是外表上更注重少加装扮的自然美.The trend at the moment is towards a more natural and less made - up look.他学会了在外表上显得呆头呆脑, 庸庸碌碌.He had learned to present a bl...