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Helium
01
氦
a chemical element that is a colorless noble gas which is lighter than air
例子
Helium is a noble gas chemical element with the atomic number 2.
As the air pressure decreased, the helium balloon began to sink toward the ground.
The balloon slowly came down to the ground after the helium escaped.
The exosphere contains a mix of residual atmospheric gases, including hydrogen and helium.
He constricted the opening of the balloon by twisting the neck tightly, preventing the helium from escaping.
