如图所示，结点O在三个力作用下平衡，保持θ不变，将B点向上移，则BO绳的拉力将

某化学课外小组模拟工业生产制取HNO₃，设计下图所示装置，其中a为一个可持续鼓入空气的橡皮球．

请回答下列问题：

（1）写出装置A中主要反应的化学方程式______．

（2）检查装置A的气密性：先将A中导管下端浸入水中，再______．

（3）已知1molNO₂与液态水反应生成HNO₃溶液和NO气体放出热量45.5kJ，写出该反应的热化学方程式______，该反应是一个可逆反应，欲要提高NO₂的转化率，可采取的措施是______

A．升高温度      B．降低温度        C．增大压强       D．减小压强

（4）实验结束后，关闭止水夹b、c，将装置D浸入冰水中，现象是______．

（5）装置C中浓H₂SO₄的作用是______．

（6）请你帮助该化学小组设计实验室制取NH₃的另一方案______（用化学反应方程式表示）．

龙卡汽车卡是国内首张Life Style概念卡，为持卡人提供（）等特色权益和服务。

A.积分加倍换油

B.优惠洗车服务

C.免费道路救援

D.高额保险服务

E.贵宾理财服务

It is hard to predict how science is going to turn out, and if it is really good science it is impossible to predict. If the things to be found are actually new, they are by definition unknown in advance. You cannot make choices in this matter. (46) You either have science or you don’t, and if you have it you are obliged to accept the surprising and disturbing pieces of information, along with the neat and promptly useful bits.
The only solid piece of scientific truth about which I feel totally confident is that we are profoundly ignorant about nature. Indeed, I regard this as the major discovery of the past hundred years of biology. It is, in its way, an illuminating piece of news. (47) It would have amazed the brightest minds of the 18th century Enlightenment to be told by any of us how little we know and how bewildering the way ahead seems. (48) It is this sudden confrontation with the depth and scope of ignorance that’ represents the most significant contribution of the 20th century science to the human intellect. In earlier times, we either pretended to understand how things worked or ignored the problem, or simply made up stories to fill the gaps. Now that we have begun exploring in earnest, we are getting glimpses of how huge the questions are, and how far from being answered. Because of this, we are depressed. (49) It is not so bad being ignorant if you are totally ignorant the hard thing is knowing in some detail the reality of ignorance, the worst spots and here and there the not so bad spots, but no true light at the end of the tunnel nor even any tunnels that can yet be trusted.
But we are making a beginning and there ought to be some satisfaction. There are probably no questions we can think up that can’t be answered, sooner or later, including even the matter of consciousness. (50) To be sure, there may well be questions we can’t think up, ever, and therefore limits to the reach of human intellect, but that is another matter. Within our limits, we should be able to work our way through to all our answers if we keep at it long enough, and pay attention.

股份有限公司是企业法人，其股东对公司承担（）。

A.经营责任

B.无限责任

C.有限责任

D.连带责任

我国地表上下的空间所有权人不可以依照自己的意志行使完全的（）。

A.处分权

B.部分处权

C.占据权

D.收益权