Can you distinguish a monopolistic competitive market from a perfectly competitive market in a few simple sentences?

The fundamental difference between perfect competition and monopoly competition lies in whether market participants have the ability to influence prices.

In perfect competition, neither individual consumers nor producers have the ability to influence prices, while monopolizing competitive markets is the opposite.

For example, for a single manufacturer, due to the above reasons, the product demand curve faced by a single manufacturer in a perfectly competitive market is a horizontal straight line, while the product demand curve faced by a manufacturer in a monopolistic competitive market is a straight line that slopes downward from left to right.

As for your question:

1.a) tap water, power companies and train tickets are all monopolies. Because the production of these public service products requires a large amount of investment in fixed assets, which creates barriers to entry. Moreover, it is impossible for such companies to operate smoothly in China without close contact with the government and a lot of rent-seeking activities, which is a huge non-profit investment. Not to mention the railway departments that provide train tickets, direct state ownership is the so-called state capital monopoly that China's political textbooks accuse capitalist countries of. B) There is no competition in China's railway field, but China's water and power companies are gradually opening to the private market, that is, competition will be introduced. Because, to a certain extent, hydropower companies can be said to be monopolistic competition.

2. China Mobile, in my opinion, is an oligopoly market, and its competitors are basically only Telecom and China Unicom. I think Sinopec can be defined as monopolistic competition and oligopoly. Because there are some oil companies in China market, you can buy them. However, there is no doubt that China Petrochemical has a dominant market share and can be listed as a leading manufacturer in the industry, so Stackelberg model in oligopoly is applicable.