读我国局部地区的水系示意图,关于泾河水文特征及原因的叙述,正确的是 ( )
A:泾河流量小,地处温带大陆性气候区
B:河流有结冰期、有凌汛现象,因为所处纬度高
C:河流水位季节变化大,与季风影响有关
D:河流含沙量小,是因为天然草场植被保护良好
阅读下面这首古诗,完成下列各题。
春日
宋晃冲之
阴阴①溪曲绿交加,小雨翻萍上浅沙。
鹅鸭不知春去尽,争随流水趁②桃花。
【注释】①阴阴:草木阴阴。②趁:追逐。
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’.
促胰液素和促甲状腺激素的靶细胞分别是( )
生活中处处有化学,利用化学原理可以防止生活中一些不良现象的产生.
(1)为保证人身安全,进入久未开启的菜窑前,必须先做 ____试验.
(2)为防止照片褪色,可将照片塑封,目的是隔绝 ____.
(3)为延长食品保质期,有些食品袋内放有一包“双吸剂”(主要成分是活性铁粉),这里“双吸剂”所吸收的物质是 ____.