问题补充:
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:
A. which
B. that
(答案→)C. what
D. who
解析: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。