Chief of the Astronaut Office procedures, and selection and conduct of specific experiments for each flight. Since the Shuttle era, the Chief of the Astronaut Office often returns to active duty in the Office once their term is complete. The Chief is currently responsible for managing Astronaut Office resources and operations, and helps develop astronaut flight crew operation concepts and crew assignments for future spaceflight missions. Chief of the Astronaut Office The Chief of the Astronaut Office is the most senior leadership position for active astronauts at the National Aeronautics and Space Administration (NASA). The Chief Astronaut serves as head of the NASA Astronaut Corps
Chinese as a foreign language Chinese language proficiency exam program, which tests has been taken around 100 million times (including by domestic ethnic minority candidates). Within China's Guangdong Province, Cantonese is also offered in some schools as optional or extra-curricular courses in select Chinese as a foreign language programs, although many require students to be proficient in the Mandarin first. Chinese is rated as one of the most difficult languages to learn for people whose native language is English, together with Arabic, Japanese and Korean. According to the Foreign Service Institute, a native English speaker needs over 2,200 hours of intensive study, taking 88 weeks