The differential cross section of the reaction e+e-→e+e- at a c.m. energy of 34.7 GeV has been measured. The result, together with our previously measured e+e-→α+α- data, are compared with the standard model predictions. We obtain for the weak neutral current couplings the values gv2=0.09×0.06, ga2=0.38×0.08. A fit of the Weinberg mixing angle gives the value gv2=0.09×0.06, ga2=0.038×0.08. The data are also used to set limits on possible deviations from the pointlike structure of leptons. An upper limit for the e+e- coupling to a heavy spin 0 boson is also given.