复句 A,in which B,at which C,by which D,from which
问题描述：
复句 A,in which B,at which C,by which D,from which
1,Last October China launched its second manned spaceship
ShenzhouVI,___two Chinese astronauts traveled in space
for five days.
A,in which B,at which C,by which D,from which
答
C
in 为从句中 修饰Chinese astronauts 和 which指代的manned spaceship 之间关系的必要介词
Chinese astronauts 不能 at,也不能 by ,更不能 from --manned spaceship
所以C