规则
Extra information that could be removed without changing the main meaning is set off by a matching pair of commas, dashes or parentheses. Do not mix them.
删去后不影响主要意思的附加信息，要用成对的逗号、破折号或括号隔开，不能混用。
✔ 正确： The bridge—completed in 1932—is now a landmark.
✘ 错误： The bridge—completed in 1932, is now a landmark.
→ 改正： Use two dashes or two commas, not one of each.
技巧: Delete the middle part. If the sentence still works, it needs matching punctuation on both sides.
练习：10题
Which choice completes the text so that it conforms to the conventions of Standard English?
由AUSLEX原创的讲解和题目，并非College Board官方资料。SAT是College Board的商标。