1, discovered by American universities. First of all, they are not interested in this problem and will not take the initiative to check it; Secondly, even if we find out, we won't have any ideas, let alone any measures.
It was discovered by American government. Same as above, unless the FBI suspects that he is an agent, add a suspicious point:)
3. It was discovered by domestic school party organizations. After returning home, the branch secretary may talk to him and ask why.
4. Those who have not contacted Party organizations abroad for a long time, whether they are branches of the original domestic schools or branches of overseas schools (if any), "those who have not participated in the Party's organizational life for six consecutive months without justifiable reasons, or have not paid Party dues, or have not done the work assigned by the Party, are deemed to have left the Party by themselves." (party constitution original)