-If you stay in China for > 6 months continuously, it is possible your physical presence continuity may be disrupted unless you prove you have the intent to live in US permanently (connection to US tightly) such as you has house in US, your family is in US, etc. If you stay in China for one year continuously (you need to have reentry permit), then your physical presence continuity will be disrupted and thus, you need another 5 years to be qualified for the US citizenship application.
另外,身体 可能会出一些问题,还可以入籍吗?
-Depends on what kind of disease you have.