PP-the Mississippi riverboat

filly

The Mississippi riverboat, which evolved from simpler steamship of the early 1800's, became the dominant form of passenger transport on the Mississippi River.

There are lots of answers for this question. Some think it should be "evolved", some think it should be "steamship", and some think it could be "passenger transport". I chose "passenger transport" at the first time. However, when I looked up the dictionary, I realized that "steamship" is the right answer based on my opinion that there is no problem for "evolved".

Transport

n. (trnspôrt, -prt)

1. The act of transporting; conveyance.
   
2. The condition of being transported by emotion; rapture.
   
3. A ship or aircraft used to transport troops or military equipment.
   
4. A vehicle, such as an aircraft, used to transport passengers, mail, or freight.
   
5. 
   
   
   
   1. The system of transporting passengers or goods in a particular country or area.
      
   2. The vehicles, such as buses and trains, used in such a system.
   
   
6. A device that moves magnetic tape beyond the recording head, as of a tape recorder.
   
7. A deported convict.

zhoushao

MM这到题有讨论过的，我不知道标题你搜一下，顺便把你的标题改改