Simply put:
If the establishment of A leads to the establishment of B, then the establishment of A is a sufficient condition for the establishment of B, and the establishment of B is a necessary condition for the establishment of A;
If the establishment of B leads to the establishment of A, then the establishment of A is a necessary and sufficient condition for the establishment of B, and the establishment of B is also a necessary and sufficient condition for the establishment of A. ..
If the title is a, then a is log (1/2) x > The necessary and sufficient conditions of 0 are: log (1/2) x > 0 can infer that a has been established, but a cannot infer that log( 1/2)>0.
log( 1/2)X & gt； 0 cannot derive X> 1/2, so AB is excluded; D is log (1/2) x >; Necessary and sufficient conditions of 0.
Options are log (1/2) x >; 0: A. No B. Sufficient condition C. Necessary and sufficient condition D. Necessary and sufficient condition