求准确翻译（as的用法）

完整的句子为“Africa had an estimated seventeen thousand white rhinos and four thousand black rhinos as of two years ago”

两年前，非洲已有大概7000只白犀牛和4000只黑犀牛。

as of“……时候,从……时候起,到……时候止,直到……

非洲有大约1700万白犀牛的,又有四千人用黑犀牛的两年前一样"

据估计两年前，非洲就已经有7000头白犀牛和4000头白犀牛。 再看看别人怎么说的。

自……起，直到…… 直到两年前，非洲已有大概7000只白犀牛和4000只黑犀牛。 例如：As of this month, police will fine people who feed pigeons. 所以从本月开始，警察将对喂食鸽子的人罚款。 Balanced, rhythmic flow, as of poetry or oratory. '韵律'。''诗歌或演讲中持平稳的节奏。 A regulated system, as of diet and exercise; a regimen. 一个有规则的制度，如饮食和锻炼（制度）；养生。 As of 2005, Stewart is once again involved in her Martha Stewart Living family of magazines. 自2005年起，斯图尔特再度专心办她的《玛莎·斯图尔特生活》系列杂志。 NASA officials say as of now, the torn solar wing is stable and seems to be delivering all its power. NASA官员表示，到目前为止，这只损坏的太阳能机翼还是稳定的，正传输着它的能量 But as of now, we count on the decisions and the paths of life that this young man, who has enriched us with such talent, makes. 但是如今，我们仰仗著这年轻男子在生活上的决心和路径，他慿藉著如此的天生才能使得我们也为之震撼。 As of yesterday, the global commodity shipping costs benchmark index - Baltic Dry Freight Index (BDI) has been dropped for three consecutive days. 截止昨日，全球大宗商品航运成本基准指数——波罗的海干散货运价指数（BDI）已连续三天下跌。 "I think to some extent, at least from the Indian context, as of now we are not seeing any significant impact, but it is [too] early to say, " he said. 卡马斯说：“从某种程度上来说，至少从印度的情况来看，到现在为止，我们没有看到任何严重的影响。但是这样说还早了点。” We are working on a sudden (as of yesterday) database performance problem. Work distribution will be slow until we fix this. Forums and other web features involving the database are currently off. 截止昨日数据库突然遇到性能问题，在解决此问题前，任务的分发将很缓慢。论坛和其他网页涉及数据库的现时正关闭。

“非洲估计有17000的白犀牛和4000的黑犀牛，这个估计和两年前的一样”