2. People usually dress in formal clothes when visiting some public places such as concert halls. It is improper to wear shorts, short skirts or jeans there. 去音乐厅等一些公共场合时，人们通常穿得很正式。在这类场合穿短裤、短裙或者牛仔裤是不合适的。
【感知】(1)It's improper to interrupt others when they are speaking. 当别人正在说话时，打断是不礼貌的。
(2)If you pronounce the word incorrectly, people may not understand you. 如果你发音不正确，人们可能听不懂你(的意思)。
(3)She sent an informal message to her friend instead of writing a formal email. 她向她的朋友发送了一条非正式的信息，而不是写一封正式的电子邮件。
【思考】形容词常见否定前缀(表示“不、无”)
• im-(多用于以p/b/m开头的词根)：im+proper→improper；im+possible→impossible
• un-：un+happy→unhappy；un+fair→unfair；un+safe→unsafe
• in-(多用于以c/r/t开头的词根)：in+correct→incorrect；in+active→inactive
• dis-：dis+honest→dishonest；dis+agreeable→disagreeable
【运用】
(1)It's (proper)to wear jeans to a wedding—people usually dress formally there.
(2)He answered the question (correct)，so the teacher asked him to try again.
(3)We had an (formal)chat over coffee，not a serious business discussion.
(4)It's (possible)for a child to carry such a heavy box—please help him.
(5)Making phone calls in the library is (proper)because it disturbs(打扰)others.

运用：(1) improper (2) incorrectly (3) informal (4) impossible (5) improper