VOA慢速英语:Scientists Look for Answers as More US Girls Enter Puberty at Earlier Age

1.Last year a study in Denmark reported an increase in early breast development. Now a new study in the journal Pediatrics adds to evidence of an increase in early puberty in American girls.

add to增加, 加强

例句：This lesson adds to the value of the book.
      这一课增加了这本书的价值。

      Since then, the palace has often been added to, rebuilt and repaired.
      从那以后, 那座宫殿不断得到扩建和修缮。

2.We followed this group of approximately twelve hundred girls on a regular basis to see when they would enter into puberty.

on a regular basis有规律的

例句：He will visit Eastern Asia on a regular basis.
      也因此，他将会定期走访东亚地区。

3. The rates, he says, were about twice as high for seven- and eight-year-olds compared to earlier studies.

twice as high倍数的表达

1) 主语+谓语+ X times + as + adj. + as
这个句型译为：① A…是B的X倍（或净增加X－1倍）.
例如：This pen (A) is twice as expensive as that pen (B).
这只钢笔(A)的价格是那只钢笔(B)的2倍。（即A比B贵一倍）
I have three times as many as you.　我有你三倍那么多。（我的比你的多两倍）
This box is four times as heavy as that box. 这个盒子比那个盒子重4倍。

2）主语+谓语+ X times+ the size (amount, width, breadth, level, value, velocity, length…) of…
  这个句型表示净增加“1倍，是…的2倍”例如：
 The earth is 49 times the size of the moon.　地球是月球大小的49倍。

compared to与…相比；比作

例句：The city is vast compared to our village.
      和我们村相比，这个城市非常大。

4.That is, chemicals that might mimic natural hormones that our body makes, or somehow interfere with how those hormones act on the body.

interfere with干预, 阻挠, 妨碍, 阻止

例句：That interferes with my plan.
      那干扰了我的计划。
 
      The noise interferes with my work.
      这噪音妨碍我的工作。

5.But he says some studies have shown that a higher BMI does not speed up development in boys, and may even slow it.

speed up(使)加速

例句：We'll never get there if he doesn't speed up.
      如果他不快些走, 我们一定到不了那里。

      We are speeding up the mechanization of our agriculture.
      我们正在加快农业机械化的步伐。