According to the Michigan study, the share of 18-year-olds who believe that using crystal meth even once or twice carries a great risk has risen every year since 2003.

密歇根大学的研究显示，2003年以来18岁上下的这一群体中有越来越多的青少年认为即使仅吸食了一两次冰毒也是有巨大成瘾危险的。

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Gullotta says a healthy man should visit the doctor every year or two. For those over 45, it should be at least once a year.

古罗塔认为一名健康的男性应该每一到两年就看一次医生。45岁以上者，应该至少每年看一次。

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Occurring once a year or every year; annual.

每年我们都有这个问题。

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Instead of visiting a branch once every year, spending advice can be pushed through to the payment device itself.

BBC: Viewpoint: The end of High Street banking as we know it

Of the top five people listed in the Thinkers 50, a once every two year ranking of influential management innovators compiled by a group of companies and media organizations, three are based at business schools.

CNN: The best business thinkers

The consolation is that it looks like commercial property in the U.S. faces a once-every-25-year flood, not the once-a-century inundation facing the nation's housing market.

WSJ: Malls, Offices May Slump Less Steeply Than Homes