Why do you think european powers
established spheres of influence in china rather than
colonies, as they did in africa and other parts of asia?

China had a firm cultural foundation. They were set in their ways and it would take a huge revolution to overthrow them. Rulers occasionally even shut down trade and isolated themselves, in order not to be influenced by European powers. They had a strong military and, most of the time, a stable government and economy. In contrast, Africa and some other Asian countries, such as India, were seen as weaker. Their military (if they had one) was easily overpowered by the western countries. They were also seen as uncivilized and primitive. Because of this, the Europeans had more respect for the Chinese than other countries. They knew that they didn't have a great chance at completely dominating the country and forming colonies.