 Complete the following phrase:  Paulus Paul Hoekstra born 30 December 1944 is a Dutch-born, Belgian retired sprint canoeist who was active from the mid-1960s to the mid-1970s. Competing in three Summer Olympics, he won a silver medal in the K-2 1000 m event at Tokyo in 1964. Hoekstra also won two medals at the ICF Canoe Sprint World Championships with a silver K-2 500 m: 