[填空题]列车控制级别分为：连续式通信的列车控制级别（ ）”，又称（ ））、点式列车控制级别（ ）模式”，又称（ ））、联锁控制级别（ ）”）。

America is a country that now sits atop the cherished myth that work provides rewards, that working people can support their families. It’s a myth that has become so divorced from reality that it might as well begin with the words "Once upon a time". Today 1.6 million New Yorkers suffer from "food insecurity", which is a fancy way of saying they don’t have enough to eat. Some are the people who come in at night and clean the skyscrapers that glitter along the river. Some pour coffee and take care of the aged parents of the people who live in those buildings. The American Dream for the well-to-do grows from the bowed backs of the working poor, who too often have to choose between groceries and rent.
In a new book called "The Betrayal of Work", Beth Shulman says that even in the booming 1990s one out of every four American workers made less than $8. 70 an hour, an income equal to the government’s poverty level for a family of four. Many, if not