Which of the following statements about securities exchanges is TRUE（）

A. Continuous markets are markets where trades occur 24 hours per day.

B. Call markets are markets in which the stock is only traded at specific times.

C. Setting a negotiated price to clear the market is a method that is never used in major continuous markets.

我国经济发展存在东部与西部的明显差异。为了发挥西部地区的优势，国家实施了西部开发战略。回答1~2题。

1．制约西部经济发展的主要因素是    [ ]

A．资金、技术不足

B．矿产资源贫乏  

C．水资源不足    

D．劳动力匮乏

2．沟通东部经济发达地区与西部资源富集地区的铁路干线是    [ ]

A．京广线    

B．京哈线    

C．陇海—兰新线  

D．青藏线