[填空题]光纤的( )、和( )是光信号受到损伤的主要原因。

{{B}}How SATS Work{{/B}}
Tests are a fact of life throughout our school careers, but one of the most important, and, to some, the scariest, of them all is the SAT—that three-hour exam that’s supposed to measure a high school student’s chance of academic success in the first year of college. Some colleges consider SAT scores major factors in their admission process, while others view high school academic performance, along with recommendations and extracurricular activities, equally, or even more importantly. No matter where you’re headed, if you’re a high school student, the SAT is important to you because most colleges require students to report either SAT or ACT Assessment scores.
{{B}}What Is the SAT {{/B}}
First of all, SAT no longer stands for Scholastic Aptitude Test (学术性倾向测验), the original name of the test when it was introduced in 1941. Although you may still see th