American people like to say "Thank you " or say something kind when others help them．People of many countries do so，too．It is a very good habit．
    You should say"Thank you'when someone passes you the salt on the table，when someone walking ahead of you keeps the door open for you and when someone says you always do your work well or you have a nice thing or your city is very beautiful．“Thank you”is used not only between friends，but also between parents and children，brothers and sisters．
    “Excuse me”is another short sentence they use．When you hear someone says“Excuse me”behind you，you know that someone wants to walk past you without touching you．It’s not polite to break(打断)others when they are talking．If you want to speak to one of them。say‘Excuse me’first，and then begin talking．You should also do so when you begin to cough or make any noise before others．
Let‘s learn to say‘Thank you’and‘Excuse me’．

生物体内的各种化学反应，几乎都是由酶催化的，请回答有关问题：

（1）甲、乙两种酶用同一种蛋白酶处理，酶活性与处理时间的关系如图所示，则初步推测甲酶的化学本质为____ ，乙酶的化学本质为蛋白质．要鉴定乙酶的化学本质，可将该酶液与____ 试剂混合．

（2）若要提高衣物上油渍的去除效果，洗衣粉中可添加酶；使用加酶洗衣粉时，水温过低或过高时洗涤效果不好的原因分别是____；____．若测定某种酶在不同温度下活性，反应液中应加入溶液以维持其酸碱度稳定，酶的活力可用来____ 表示．

如图，□ABCD中，E为AD的中点．已知△DEF的面积为S，则△DCF的面积为（    ）

根据拼音写出相应的词语。

①她qiáo cuì____的脸上现出央求般的神气。

②小鸭是那么丑陋，他处处挨啄，被排挤，被shàn xiào____。

③一生中的每时每刻都在消磨人的青春和力量，直到huà wéi wū yǒu____。

④小屋cū zhì làn zào____，出自一个农村木匠之手。