uranium-actinium

例句：

1. 1. Uranium is a rare and valuable element that is used in nuclear power plants.
   铀是一种稀有且宝贵的元素，用于核电站。
2. 2. Thorium is a similar element to uranium but with a higher atomic number.
   钍与铀类似，但原子序数更高。
3. 3.The discovery of uranium and thorium has led to the development of nuclear energy.
   铀和钍的发现推动了核能的发展。