In 1955, a man named Raymond Kroc entered a partnership with two brothers named McDonald. They opened a popular restaurant in California which sold food that was easy to prepare and serve quickly. Hamburgers, French fries, and cold drinks were the main food there. Kroc opened similar eating places under the same name, “McDonald’s”, and they were an instant success. He later took over the company, and today it is one of the most famous and successful “fast-food” in America and round the world.  
Why was his idea successful? Probably the most important reason was that his timing was right. In the 1950s, most married women stayed home to keep house and take care of their children. In the 1960s, many women returned to the workplace. This meant that they had less time or energy to prepare meals, so they spent more on “ TV dinners ” and fast-food restaurants. Single parents also have little time to spend in the kitchen. People living alone also depend on this type of food, since cooking for one is often more trouble than it is worth.
Fast-food is not part of the diet of all Americans. Another trend of the 1960s, sometimes called the back-to-nature movement influenced many people to avoid food that was packaged or processed(处理). This preference for natural food continued to this day.
From the success of Raymond Kroc’s fast-food business, we can say that social economic trends influence where and what we eat.
The underlined sentence “Cooking for one is often more trouble than it is worth” means that ______.

A．cooking for some people is worth more money

B．it is not worthwhile to take too much time to cook for one person

C．there are more problems when one person cooks

D．divorce (离婚) causes people to change their eating habits

An idea implied but not directly stated in the reading is that ________.

A．many married women began to work in the 1960s

B．natural foods are still popular today

C．fast food is not part of the diet of all Americans

D．divorce causes people to change their eating habits

McDonald’s success lies in the following causes BUT_________.

A．people living alone tend to depend on fast food

B．single parents have little time to spend in the kitchen

C．many women returned to the workplace in the 1960s

D．Kroc chose the “Mc Donald” brothers as his partners

The main idea of the reading is that ________.

A．Raymond Kroc is the most successful fast-food business owner in the world

B．social and economic changes affect eating habits

C．fast-food is easy to prepare and serve quickly

D．Americans eat either fast food or natural food