and or but so

But at about age 15 or so, the men voluntarily began cutting down their nightly sleep time because of pressures from school, work, and other activities.

但在大约15岁左右的时候，由于学校、工作和其他活动的压力，这些男性自愿开始减少夜间睡眠时间。

No one keeps an exact count, but rough calculations based on the government's survey suggest that perhaps 1,600 American public and private schools are teaching Chinese, up from 300 or so a decade ago.

没有人知道确切的数字，但是根据政府的调查，粗略计算之后显示，大约有1600所美国公立和私立学校在教授中文，而十年前只有300所左右。

So what about those questions/comments like: "I wish I could take this class, but I can't take three days off or travel." and so on?

所以我们就有了以下这些问题/评论：“我希望可以参加这个课程，但是我不能请三天的假或者花在旅程上”或者等等？