Continuing education: It refers to non-academic education for professional and technical personnel for the purpose of updating, supplementing, broadening professional knowledge and training, and improving business capabilities. According to the above definitions, Which of the following are continuing education:. ['Many rural middle school teachers have obtained undergraduate diplomas through correspondence education.', 'Colleges and universities have obtained professors, associate professors, and teachers for doctoral degrees.', 'To adapt elementary school teachers to the new curriculum standards, the Education Bureau conducts summer training for three consecutive years.', 'Various forms of vocational training organized by the Labor Bureau to help laid-off workers achieve reemployment.']