[求助]语法

Karenwu

1.” ....within the next few hundred years",请问"hundred"要不要加＂Ｓ＂，ＷＨＹ？

２. The Mississippi riverboat, which (evolved )from simpler (steamship) of the early 1800s,became the (dominant) form of (passenger transport) on the Mississippi River.
为什么B错。用单数可以吗?

2. The various (peoples) who (developed) North America( have made it )a world (leader economic).
D明显错。但A为什么对？

xeonxeon

1. two hundred years和hundreds of years是正确用法, 表示数目的词前面有限定词的时候都用单数，如这里的few
2.我试着解释一下，这里是说riverboat是从steamship发展来的,显然，这里的steamship是指的一类船而不是单独的一艘船，所以用复数。
3. peoples用复数表示不同种类的人，比如黑人，白人，黄种人...

Karenwu

Thanks a lot!