问题
选择题
The companies are working together to create ________ they hope will be the best means of transport in the 21st century.
A．which
B．that
C．what
D．who
答案
答案：C
C 考察名词性从句。此处缺少宾语从句的连接词，而从句________ they hope will be the best means of transport in the 21st century中they hope是插入语，因此缺少主语，所以起双重作为what。