问题
选择题
Stephen Hawking has expressed his opinion ___ humans might one day be able to make spaceships capable of such speeds that time on board would slow down．
A．that
B．whom
C．which
D．what
答案
答案：A
考查名词性从句。句中考查that引导的同位语从句，解释说明名词his opinion，在句中不作任何成分，故选A。