我想说的是,我相信有证据表明,在欧盟公投期间存在道德不端问题。本句为简单句。该句主干为i believe there is evidence;.of引导的为evidence的后置定语。Suffice to say为固定搭配,意为“我只想说,无须多说,可以说”。例如:Suffice to say,jobs are scarce and with no guarantee of iy,there's little to encourage young graduates to stay.译文:可以这样说,工作稀缺而且没有安全保证,年轻人很难留在这里工作。