ucting the students to correct their attitudes to-ward learning, consolidate the professional thinking, intensify their critical thinking awareness, then further improve the masters' ability of critical thinking.

To construct retroviral vector carrying human interleukin-3 c0mplementary DNA(HuIL-3 cDNA) under control of human a-fetoprotein gene enhancer core sequence and human SV4O pro-moter. Methods and Results: HuIL-3 cDNA was inserted into polylinker site of retroviral vector pMNSMto construct retr0viral vector pMNS-IL-3, in which the transcription of HuIL-3 cDNA was drived by SV40early region promoter. Human Q-fetoprotein gene enhancer core sequence was released from plasmidpGEM. 7Zf-AFPe and inserted into the polylinker site of pMNSM. Then human interleukin-3 cDNA wasinserted int0 p0lylinker site to construct retroviral vector pMNSA-IL-3, in which HuIL-3 cDNA transcrip-tion was drived by SV40 early region promoter and enhanced by human a-fetoprotein enhancer core se-quence- Conclusion: The vectors are of significance for hepatoma-specific gene therapy.