规则
A sentence needs a subject and a main (finite) verb and must express a complete idea. A group of words without these is a fragment.
句子需要主语和谓语动词（有时态的动词），并表达完整意思。缺少这些的词组是句子片段。
✔ 正确： The museum, which opened in 1990, attracts many visitors.
✘ 错误： The museum, which opened in 1990 and attracts many visitors.
→ 改正： Remove "and" so that "attracts" becomes the main verb.
技巧: Cover the extra information between commas. If what remains has no main verb, it is a fragment.
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。