There are three ground rules you need follow

您需要遵循三个基本规则

youdao

There was a couple on the second floor, and two women and three kids on the ground floor, but no one was badly hurt.

二楼有一对夫妇，一楼有两名妇女和三个孩子，但没有人受重伤。

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The hotel is set on three floors. There's a bar and cafe at ground level.

旅馆有三层楼。底层有个酒吧和咖啡厅。

《柯林斯英汉双解大词典》

Also,the root can stay in the ground for as long as three years, so it can be harvested as needed.

VOA: special.2010.06.08

The plan now is to have about a thousand and nine hundred something civilian people on the ground in Afghnastan by New Years Day which is about three times of we had last year.

现在的计划是说我们将要派大概1900平民到阿富汗,在新年之前,这个数量是去年的三倍之多。

普林斯顿公开课 - 国际座谈会课程节选

Roots of Peace says a landmine costs anywhere from three to thirty dollars to produce and place in the ground.

VOA: special.2010.05.03

What sets Portland, Oregon-based CytoDyn (CYDY) apart from the pack is its pipeline of three ground-breaking therapies, PRO 140 and Cytolin entry-inhibitor antibodies for R5 HIV-1 (the most common, most virulent strain of HIV worldwide).

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Targeted and tweeted just under a week ago, shares of Oracle Corporation (NASDAQ: ORCL) have since climbed by nearly three and a half percent, gaining ground for three days in a row (and heading higher today on Tuesday) after making The Stock List roster.

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These are linked to a Civil Defense bunker, three stories under ground level.

CNN: Singapore boosts security with tech