某一不可逆化学反应（）在无酶和有酶催化时均可以进行，当该反应在无酶条件下进行到时间t时，向反应液中加入催化该反应的酶。下图中能正确表示加酶后反应物浓度随反应时间变化趋势的曲线是   

Dear Liz,

    Thank you very much ____ your letter and the photos of your ____ (friend) and family. Your parents and friends look really nice ____ the photo. Now I can tell you something about me and ____ (I) family here in New York.

    I've got two brothers. ____ (they) names are Lukas and Andreas and they ____ (be) 16 and 19. My mother is French and her name is Christine. Dad is American and his name's Dieter. Our house ____ (have) got four bedrooms and a small garden. My room is tidy, but my ____ (brother) is not. They don't often clean it. We have a dog, Zak, and we think he's cute. We ____ (love) it a lot.

    Please tell me all about ____ (you) friends and school in your next letter. I'd like to know about English schools.

Love,

Laura

读课文《好伙伴》，把标点符号补充完整。

①  ____猎狗____你究竟在哪里呀____马哈多抬头望望乌鸦____

②  马哈多心理想____它把肉叼到哪里去了呢____我得弄明白____

读课文《济南的冬天》，“最妙的是下点小雪呀！”一段描写景物的顺序是：①____②____③____④____

21世纪将是（    ）

①知识迅猛增长的时代                   ②终生学习的时代

③注重人的潜力和价值的时代       ④国际竞争日益激烈的时代