The debate over washing dishes by hand vs using a dishwasher has been on TreeHugger since it faced the world. In the earliest article I could find from 2005， the dishwasher came out the clear winner, with researchers from the University of Bonn saying it uses only half the energy and one-sixth the water.
Fifteen years later, we're still talking about it, and a new study published in the journal Environment Research Communications shows not much has changed. Dishwashers still take the prize for efficiency（效率），both in terms of energy and water used. The findings are interesting because kitchen cleanup is something we do every day, so why not learn the best way？
Forty participants were required first to load and run a dishwasher and then to wash dishes by hand the way they would at home. They answered survey questions afterwards about their dish washing behaviors. Three other participants were then required to load a dishwasher and wash dishes by hand following best practices. This meant not pre-rinsing（预冲洗）dishes before loading them in the dishwasher and using the recommended normal cycle with heated dry,rinse-aid, and high-quality cleaner. For washing dishes by hand, this meant using the two-basin method "where dishes are soaked（浸泡）in hot water,rinsed in cold water, and are air-dried."
These "best practices" differ from typical dish washing behaviors. Most people pre-rinse their dishes before loading them into a dishwasher. They also run the tap while washing by hand, which wastes large amounts of water, and rinse with hot water. The researcher found that these typical practices produce "5，620 and 2，090 kg of greenhouse gas emissions（排放）based on washing 4 loads a week for 10 years. " So the dishwasher was less than half as bad as hand-washing, even when improper techniques were used.
When it comes to water usage, the benefits of dishwashers continue. Over the course of ten years, a dishwasher will use 16，300 gallons of water,99.8 percent of which comes from daily use； whereas, washing the same number of dishes by hand for ten years will use 34，200 gallons.



What did people think of the dishwasher fifteen years ago？ ______

A. It was expensive.
B. It was effective.
C. It was of little use.
D. It was harmful.

What were the forty participants asked to do during the experiment？ ______

A. To wash dishes as they usually do.
B. To wash all the dishes without soaking.
C. To use the two-basin method for a week.
D. To ask questions about doing housework.

What is the typical way of washing dishes with a dishwasher？ ______

A. Tuning of the water tap during the process.
B. Soaking the dishes in hot water first.
C. Washing dishes four times a week.
D. Rinsing the dishes before loading them.

How much water can be saved with a dishwasher over ten years？ ______

A. About 5，500 gallons.
B. About 16，000 gallons.
C. About 18，000 gallons.
D. About 34，000 gallons.