When the Erie Canal was built in the 1820's, it was the engineering marvel of its time.

A．wonder

B．dispute

C．frustration

D．model

下列物质放入水中，能形成溶液的是　　　　　　　　　　　　　　　　　　　　　　 [ ]

A．石灰石

B． 纯碱

C．汽油

D．面粉