Velez and other fire fighters throughout North America, who give similar presentations, will never know how many lives they save through their talks.

维勒兹和其他北美的消防员也做过类似的报告，他们永远不知道他们的演讲拯救了多少人的生命。

youdao

That said, we know of many Postcrossing members, including Chinese, who have actually improved their English skills through their use of Postcrossing.

尽管如此，我们知道许多 Postcrossing 会员，包括中国人，通过使用 Postcrossing 提高了英语技能。

youdao

Many people still find out about jobs through someone they know, and not through advertisements.

仍然有很多人是通过认识的人而不是通过广告找到工作的。

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"For many of the women who walk through our doors, confidence is a huge issue, and I know,many of the women who I've worked with have said to me, 'you know Suzanne, no one has ever said to me, I believe in you,' Elliott says 70 percent of the women helped by the group are single mothers.

VOA: standard.2009.12.25

You know, it's a great place. I've walked through there many times.

那是个好地方。我路过那儿很多次。

哈莱姆很独特 - SpeakingMax英语口语达人

So this means we can actually calculate this for any molecule that we've drawn the Lewis structure for, because we actually do need to draw the Lewis structure before we know, for example, how many of each of these we have, or at least go through the rules.

这意味着我们可以将原来画过,路易斯结构的分子的形式电荷计算出来，因为我们其实在画出,路易斯结构之后才能知道，比如，这些量的值是多少，或者至少我们需要经过前面的那些步骤。

麻省理工公开课 - 化学原理课程节选

Etsy says it doesn't know how many sellers make a living through its site and says it doesn't know how many people sell on its site as a full-time job.

WSJ: Busted by the Crafts Cops

We can go back and process every video of Times Square ever taken and know how many times someone passed through, and with whom.

FORBES: While You Slept Last Night... Big Data, Privacy and the Public Square

Ms Colby says schools often do not know what services are available and many children slip through the net and don't get the advice they need.

BBC: News | Health | ME children need help with education