短语讲解：

1. The average child will eat 1,500 peanut butter and jelly sandwiches before he or she graduates high school, according to the U.S.-based National Peanut Board.

according to 根据
例句：According to the normal,I should accept her invitation.
按照常情，我应该接受她的邀请。

2. But medical experts worry about adults who rely too heavily on caffeine.

worry about 担忧， 烦恼; 惦念
例句：Don't worry about being late. It's fine.
别为迟到担心了 没有关系。

3. United States Senator Charles Schumer says he worries about the effects on children from a product never before associated with caffeine.

associate with 与…交往， 联系
例句：I only associate with good decent fellows.
我只和正派的好人交往。