逗号是ACT考试中被看到最多次的标点,它主要有5种用途。

      1、用于连接一个句子中主语、谓语、表语、宾语、定语的并列成分。当并列成分,有三个或者三个以上,最后一个需要用逗号隔开。      如:Having found the leaking pipe, the plumber cut off the water, replaced the pipe and told the homeowner to call him if the leak recurred.      2、 用于分隔同位语      如:Alice and her sisters, all scuba divers, spend a week diving at Marathon in the Florida Keys every year.      3、用于分隔至于句首或插在句中的状语或状语从句      如:Since you are in poor health, you should not stay up late.      4、用于分隔非限制性定语从句     如:My grandfather, who smokes a lot, is ninety.

     5、 用于分隔插入语

     如:Some parents, it appears, are more concerned about their children’s test scores.