图中，与∠1成同位角的个数是（　　）

根据句意及所给中文提示或英文解释，写出句中所缺单词，每空限填一词。
(1)Keep a____ (微笑) all the time, you'll have a happier life.
(2)The weather report says it will be ____（有雨的）. Please take an umbrella with you.
(3)Drivers should ____ （停车）their cars in the right place, or they will be fined.
(4)Audrey Hepburn had put her ____ （努力） into ballet training before she entered the film industry.
(5)Daniel's____ （努力）is to be a famous director in the future.
(6)Zhang Sen was a brave young man. He____ (keep somebody safe from danger)a young lady from a river several months ago.
(7)Our teachers are____  (treating every person equally) to everybody in our class. We all love them.

若等腰三角形的两边长分别是2和10，则它的周长是（　　）