Space is a dangerous place, not only because of meteors(流星), but also because of rays from the sun a

B．the protection from space radiation is no easy job
C．astronauts may possibly have deformed children or grandchildren
D．radiation is not a threat to well-protected space explorers
53．Which of the following is TRUE?
A．Space is dangerous only because of meteors.
B．Explorers in space have to avoid the damage from radiation
C．We have got effective ways to treat illnesses caused by radiation.
D．The atmosphere doesn’t screen off radiation

答案D B D C B