  In the derivation of Bell's inequalities, probability distribution is
supposed to be a function of only hidden variable. We point out that the true
implication of the probability distribution of Bell's correlation function is
the distribution of the joint measurement outcomes on the two sides. So it is a
function of both hidden variable and settings. In this case, Bell's
inequalities fail. Our further analysis shows that Bell's locality holds
neither for dependent events nor for independent events. We think that the
measurements of EPR pairs are dependent events, thus violation of Bell's
inequalities cannot rule out the existence of local hidden variable. In order
to explain the results of EPR-type experiments, we suppose that polarization
entangled photon pair can be composed of two circularly or linearly polarized
photons with correlated hidden variables, and a couple of experiments of
quantum measurement are proposed. The first uses delayed measurement on one
photon of the EPR pair to demonstrate directly whether measurement on the other
could have any non-local influence on it. Then several experiments are
suggested to reveal the components of polarization entangled photon pair. The
last one uses successive polarization measurements on a pair of EPR photons to
show that two photons with a same quantum state will behave in the same way
under the same measuring condition.
