Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| # | Name | Alma mater | Birth date | Marriage date | President | Tenure | Tenure |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | Jiang Qing | Shandong Provincial Experimental Theatre | 19 March 1914 | 20 November 1938 | Mao Zedong | 27 September 1954 | 27 April 1959 |
| 2 | Wang Guangmei | Fu Jen Catholic University | 26 September 1921 | 21 August 1948 | Liu Shaoqi | 27 April 1959 | 21 October 1968 |
| 3 | He Lianying | N/A | N/A | N/A | Dong Biwu | 31 October 1968 | 17 January 1975 |
| 4 | Lin Jiamei | Tong De Medical College | 1924 | N/A | Li Xiannian | 18 June 1983 | 8 April 1988 |
| 5 | Wang Yeping | Shanghai Foreign Language Institute | February 1928 | December 1949 | Jiang Zemin | 27 March 1993 | 15 March 2003 |
| 6 | Liu Yongqing | Tsinghua University | 1940 | February 1970 | Hu Jintao | 15 March 2003 | 14 March 2013 |
| 7 | Peng Liyuan | China Conservatory of Music | 20 November 1962 | 1 September 1987 | Xi Jinping | 14 March 2013 | Incumbent |
Question:
dong biwu served in 1975. who was the previous president?
Answer:
Liu Shaoqi