助动词do/does/did +not +动词原形
American professors did not possess one.
They do not fund peer-reviewed research.
助动词和情态动词(be动词，情态动词，完成时态中的have等) +not
To be sure, the future is not all rosy.
With other audiences you mustn't attempt to cut in with humor...
average height... hasn't really changed since 1960.