 By Humeyra Pamuk and Michael Martina WASHINGTON Reuters - Katherine Swidan, whose son Mark has been imprisoned in China for over 10 years, has not seen even a photograph of him over the last decade. The last time she heard his voice was in 2018. She and the families of other Americans, who according to the U.S. government are wrongfully held in China, are hoping that the U.S. Secretary of State Antony Blinken can push the Chinese authorities for the release of their loved ones as he visits Bei... 