the companies are working together to create ____ they hope will be the best means of transport in the 21st century.A.which B.what 为什么不选a?

the companies are working together to create ____ they hope will be the best means of transport in the 21st century.
A.which B.what 为什么不选a?

这是定语从句和宾语从句的纠结了~
你看,the companies 是要 create 是个什么东东是吧~
所以create后面的,全部都是“东东”,也就是所谓的宾语.
那么引导宾语从句,显然不能用“which”咯~
如果这句话在create后面加一个“way”"means"之类的可以做宾语的.如：
the companies are working together to create a way____ they hope will be the best means of transport in the 21st century
那么这时候“东东”就变成了“a way”（一种方法）,而后面的全部变成了修饰way的~,也就是传说中的定语,这时候,题目摇身一变成了定语从句~
临表涕零,不知您听懂了没有~

What既可以充当主句中某个成分，也能充当从句中的某个成分，在本题中What一方面充当Create的宾语，另一方面充当从句中they hope的宾语；而Which通常情况下只能充当从句中的某个成分，因此选择What。