Several German states have banned teachers from wearing the headscarf.德国也有若干州禁止教师这么做.She pushed all her hair under a headscarf.她把头发都让头巾罩住.A long thin wool coat and a purple headscarf protected her against the wind.一件薄薄的羊...
Protons are nearly 2000 times as heavy as electrons.质子的质量几乎是电子的2,000倍。The neutrons and protons form the core of the atom.中子和质子构成了原子核.Electrons are negatively charged with electricity, protons are positively charged.电子是带负...