碳钢材料制造的阀门，规定使用温度不得高于（）℃。A、350； B、400； C、45

花园、庭院中的花盘和石块下，常常会看到一些身体略扁、长椭圆形、灰褐色或黑色的小动物--鼠妇在爬行，还会发现潮湿的地方鼠妇很多，这是为什么呢？某生物兴趣小组对此进行探究，请你将探究活动的过程填写完整。  

(1)提出问题：________________？

(2)作出假设：________________。

(3)制定并实施探究方案：在铁盘的一半放湿土，另一半放干燥的土，将10只鼠妇放在两种土的交界处，放在适宜的环境下，认真观察鼠妇的行为。

(4)分析实验结果，得出结论。该小组对上述实验重复10次，结果如下表：

(5)在实验重复10次的原因是：_______________。

(6)根据以上的观察和计算出它们的_____________值；得出的实验结论是_______________________。

将实验室制取二氧化碳和用高锰酸钾制取氧气进行比较，下列说法正确的是（　　）

A．气体发生装置可能相同

B．反应条件相同

C．气体收集方法可能相同

D．反应的基本反应类型相同

某投资方案，当所设定的r1值为12%时，该方案的净现值为260万元；当所设定的r2值为18%时，该方案的净现值为-360万元。则该方案的内部收益率是（　）。

A．9.48%

B．11.52%

C．15.52%

D．16.285

Password (密码) strength has been a topic about the Internet lately. I have seen lots of clever methods for generating and remembering strong passwords. Some are better than others, but in my opinion, none are adequate. Here's the problem: It doesn't matter how strong your passwords are if you use the same one on multiple sites. All it takes is for a site to get hacked(侵入), like Gawker media, or even Sony did, and now your super­strong password has been stolen, and every site on which you used that password has been accessed.

So, the bottom line is that no matter how strong your passwords are, and no matter what clever tricks you use to help you remember them, if you surf internet often, the only truly secure password system is what you need.

Enter LastPass. It's not the only password manager out there, but I like it the best. You create ONE strong password that you have to memorize and use it to access your LastPass database. The LastPass database is stored online, on LastPass's servers. LastPass recognizes the site you're on and automatically logs you in (after, optionally, asking you to re­enter your master password). LastPass also has automatic form fill and automatic password generation. This means that you can have a different, unique, very strong password for every site you log into, but you only have to remember one master password. It's the best of both worlds.

One argument against LastPass is that if their database is attacked, then all of your sites are in danger, and that's true, but given that their entire line of work is keeping that information safe, I'm willing to take that chance. The alternative is rolling dice(掷骰子) or picking phrases to create passwords, writing all of them down on a piece of paper or something, and then having to manually type them in when I go to a site. A terrible mess.

There is a free version of LastPass, with some additional features unlocked if you pay a $12 a year subscription.

­Joshua Bardwell 

小题1:The writer thinks using the same password everywhere is ________.

A．dangerous

B．convenient

C．appropriate

D．adequate小题2:When using Lastpass, users have to remember ________.

A．all passwords used

B．the last password

C．unique password each time

D．the master password only小题3:Critics are against Lastpass because ________.

A．they have better ways to create password

B．they think rolling dice is more convenient

C．they have no faith in Lastpass database's safety

D．Gawker media and Lastpass were hacked once小题4:Joshua Bardwell writes the passage to ________.

A．share his experience

B．introduce a product of good quality

C．advertise his product

D．teach how to use a new product

宴会除了提供一般的餐饮产品外，还具有以下典型的特点（）

A.社交性

B.规格性

C.群集性

D.一次性

E.丰厚性