The (down) is one of six types of quarks (constituent particles of protons and neutrons) having a negative electric charge. （向下）是六种带负电荷的夸克（质子和中子的组成粒子）之一。
2
u quark
上夸克
The (up) is one of six types of quarks (constituent particles of the protons and neutrons) having a positive electric charge. （up）是六种带正电荷的夸克（质子和中子的组成粒子）之一。
1
d quark
d 夸克
The (down) is one of six types of quarks (constituent particles of protons and neutrons) having a negative electric charge. （向下）是六种带负电荷的夸克（质子和中子的组成粒子）之一。
2
u quark
上夸克
The (up) is one of six types of quarks (constituent particles of the protons and neutrons) having a positive electric charge. （up）是六种带正电荷的夸克（质子和中子的组成粒子）之一。
