大一点的是气体行星，它们的硬质表面深埋在氢氦层低。
Larger worlds are gassy, with their solid surfaces buried beneath deep blankets of hydrogen and helium.
所有的稀有气体元素的最外层电子数都是该层最大的可能数目：氦的最外层电子有两个，其它的稀有气体最外层电子数是八。这使稀有气体非常稳定。
All noble gases have the maximum number of electrons possible in their outer shell (two for helium, eight for all others), making them highly stable.
这些卵石层反应堆运作的方式是，氦从这面的上面进来，然后，通过这个卵石层再出去，这不是液化层。
The way these pebble bed reactors work is the helium comes in up the side and down through the pebble bed. It's not a fluidised bed.
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