单项选择题
A．the Apollo mission was very successful B．protection from space radiation is no easy job C．astronauts will have deformed children of grandchildren D．radiation is not a threat to well protection space explorers
A．The Atmosphere and Our Environment B．Research on Radiation C．Effects of Space Radiation D．Importance of Protection Against Radiation
A．their English is not good enough B．they are afraid they might meet with unfair judgment in these areas C．there is a wide difference between Asian and Western cultures D．they know little about American culture and society