如图，小明从路灯下A处，向前走了5米到达D处，行走过程中，他的影子将会（只填序号）____ ①越来越长，②越来越短，③长度不变．

在D处发现自己在地面上的影子长DE是2米，如果小明的身高为1.7米，那么路灯离地面的高度AB是____ 米．

凝乳酶能催化乳汁凝固，常用于奶酪的生产．为探究温度对凝乳酶活性的影响，某同学设计了如下实验：

①取若干试管，分为A、B、C、D、E、F六组，每组两支试管，其中一支试管放入2mL凝乳酶，另一支放入2mL乳汁．

②将六组试管分别置于不同温度水浴15min．

③将每组试管中的凝乳酶和乳汁混合后在原温度下继续水浴，记录凝乳所需时间，结果如下表．

请回答问题：

（1）上述实验结果中，凝乳所需要的时间越短，表明酶的活性越____ 

（2）A组中乳汁不凝固的原因是____ ．F组中乳汁也不凝固，若将其温度冷却至40℃，乳汁将____（会、不会）凝固，原因是____ 

（3）通过以上实验，____（能、不能）得出“凝乳酶的最适温度是40℃”的结论．

人民生活已小康，请客吃饭讲排场。人多地少粮紧张，“光盘行动”当弘扬。

支原体感染引起的传染性尿道炎较难治愈．如图是支原体细胞结构示意图，相关叙述正确的是（　　）

任务型阅读

When you start a new school, go to a party or try to know a person, you often need to break the ice in order to start a friendly conversation. Breaking the ice means saying or doing something to stop feeling shy or uncomfortable around someone you don’t know well. Almost everyone feels uncomfortable or shy when people meet for the first time. If you feel like this, the following ① tips can help you out.

Smile ② Whenyou smile, people think you're friendly and easy to talk to. They are also very likely to smile back and help you feel more comfortable about starting a conversation.

Be positive  Everybody likes being around happy people. Always look on the bright side of life and see everything positively（积极地）.

Be a good listener.   Don't control the conversation and don't just talk about yourself. ③ 仔细听别人讲，并且问一些关于他们自己的问题。They'll think you're worth talking to.

Be easy-going  ④ Some people may be so shy that they can't break the ice. Don't avoid being around new people just because you feel uncomfortable. If you face a situation again and again, you'll get used to it.