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A,B,C,D,E,F为原子序数依次增大的短周期主族元素.A、F原子的最外层电子数均等于其周期序数,F原子的电子层数是A的3倍;B原子核外电子分处3个不同能级且每个能级上的电子数相同;A与C形成的分子为三角锥形;D原子p轨道上成对的电子总数等于未成对的电子总数;E原子核外每个原子轨道上的电子都已成对,E电负性小于F.
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    Amsterdam is a special city. There are many places you should not miss during your visit. Here is our list of the best.

Amsterdam canal ring

    The city old centre is formed from canal rings, which give you the feeling of space, freedom and peace. Walk through these canal streets or better — take a trip by renting a boat yourself. Another way to explore the Venice of the North is to take a ride on a bicycle. Any way you decide for - enjoy this city.

The National Maritime Museum

    The Maritime Museum is an attractive place to visit, especially with children. With many attractions in it, this colourful and enjoyable museum will help you understand the history of the Netherlands - a small nation which was one of the world's greatest sea powers.

Amsterdam Brown Cafe

    When you enter Amsterdam old cafes called Brown, at first it will seem too much from the past and too crowded, but the atmosphere is unique. Relax and watch - most of people around will be locals. Feel like one of them — the real Amsterdammers.

Civic Guards Gallery

    This gallery is filled with old paintings from the Dutch Golden Age. The exhibited canvas may be not always the masterpieces of art, but these group portraits of Amsterdam citizens and their wives are an exquisite (精致的) document of the Dutch civilization and culture centuries ago.

To avoid waiting lines we advise you to buy your tickets in advance online through our Amsterdam attractions and museums tickets webpage.