We can never forget the days the two astronauts in spaceship worked together and the days

问题补充：

We can never forget the days the two astronauts in spaceship worked together and the days we spent together.A. when; whichB. which; whenC. what; thatD. on which; when

答案：

选择定语从句的关系词关键在于区别关系词在从句中作什么成分。第一个先行词the days在从句中作状语，故用when或on which；而第二个the days在从句中作spent的宾语必须用which或that。综合两个空，只能选A。