Mercer consulting has released its annual ranking of the world's best cities. The rankings were judged based on 39 factors, including city infrastructure, quality of life, road traffic, airline connections, economy, medical access, crime levels, education, housing and others. The top city worldwide was Vienna, Austria.

The top cities in the U.S. were both Pacific Ocean cities: San Francisco and Honolulu. Canada's Pacific city of Vancouver ranked ninth overall.

Many European cities were in the top 25 of the more than 200 cities in the study. Mercer gave top infrastructure scores to the German cities of Frankfurt and Hamburg, and Denmark's capital Copenhagen.

Among Asian cities, the highest-ranked was Singapore (25th overall). Tokyo and other Japanese cities ranked below the Asian top ten. ranked 44th and Kobe 48th.

Singapore was also ranked number one worldwide for infrastructure.

Dubai ranked top in the category of infrastructure for the Middle East.

weather permitting

Dale: What time is your flight to Tokyo?

Tim: It takes off at 5:00 and, weather permitting, it should land at 7:00.

Explanation: The phrase "weather permitting" is a way of saying that the plan will only happen if the weather is good. We use this phrase when planning things like flights, picnics, and outdoor sports events.

ambu bag

Doctor Smith: We need to move this patient to another hospital for treatment

Paramedic: I'll keep him breathing with an ambu bag inside the ambulance. We only need a few minutes to get to the next hospital.

Explanation: An "ambu bag" is a mask with a soft bag attached that is pressed with the hand in order to push air into a victim's lungs. It is used to help a patient breathe when they are being moved from one place to another when an oxygen tube is not available.

on the back burner

Dear Mr. Watkins:

We got your question about importing the new sunglasses we wanted to manufacture. But because of the bad economy, that project is on the back burner. Perhaps we can restart the project in a few years.

Explanation: The "back burner" means the back two burners of a kitchen stove that has four burners. We say that something is "on the back burner" it means that it's not an important thing to us anymore. We are concentrating on something else.