Morning to Milan . Visit Cathedral Duomo Square, Emmanuel II arcade . Afternoon to Luzern.早上前往米兰观光包括米兰大教堂、广场及伊曼纽二世商店中心,下午前往瑞士卢森....a shopping arcade.室内购物商场We go to the amusement arcade on Saturdays to play the electronic...
质子的质量几乎是电子的2,000倍。Protons are nearly 2000 times as heavy as electrons.质子是物质的基本粒子。A proton is an elementary particle of matter.中子和质子构成了原子核.The neutrons and protons form the core of the atom....