移民后还能回国长住吗?

The answer is no.

After you become a citizen of another country, you have surrendered your Chinese citizenship.

You can continue to use your Chinese passport to return and live in China until your passport expires. After that, you will never have a Chinese passport again.

That's simple. Without a Chinese passport, how can you return to China without a visa.

I have 2 friends: one from Shanghai and the other Hong Kong, and both Canadian citizens. The one from Shanghai has to obtain a visa every year to visit China. The other from Hong Kong can apply for a entry permit for Hong Kong residents only, so he can go to and live in China without a visa.

移民后如果你考上了公民，一年至少有半年时间要在那边了

回国住一两个月应该没问题吧