In 'come back', 'break down' and 'fall off', 'back', 'down' and 'off' are all adverbial particles.

在come back、break down和fall off中，back、down和off都是副词小词。

《牛津词典》

Inflation could fall back into single figures as early as this month.

通货膨胀最早在本月就能回落到一位数。

《柯林斯英汉双解大词典》

He has her support to fall back on when the going gets tough.

当进展艰难时，他可以依赖她的支持。

《柯林斯英汉双解大词典》

At the end of July, the roommates said goodbye, as they started summer recess and headed back to their home states to gear up for the fall re-election campaign.

VOA: standard.2010.08.07

Well, I actually think the Russian formalists can be defended against the charge that, unbeknownst to themselves, they fall back in to form-content distinctions by insisting on this variety of dualities.

但是我认为,这些形式主义者们在不自觉中，对于形式和内容的双重性,太过偏执。

耶鲁公开课 - 文学理论导论课程节选

If low growth comes to pass - if growth stagnates and unemployment refuses to fall back - the IMF recommends a new round of quantitative easing by the Bank of England combined with "temporary tax cuts" aimed at people on low incomes, investment and job creation.

BBC: IMF set out a 'Plan B' for George Osborne

At the very least, small-scale and low-tech gemstone-mining could be a fall-back for the country's beleaguered herders.

ECONOMIST: Somaliland

There are nearly twenty states that have implemented sales tax holidays in conjunction with the annual back-to-school promotions in early fall.

FORBES: Move up http://i.forbesimg.com t Move down