影响苯塔顶温度变化的原因有哪些？对操作有何影响？

当血铅浓度超过生物限值时，表示接触者（）

A.有铅接触史

B.有过量铅接触

C.有轻度铅中毒

D.有中度铅中毒

E.有重度铅中毒

宏观经济学中，表示失业率和工资增长率之间存在着负相关关系的曲线是( )。

A．洛伦茨曲线

B．菲利普斯曲线

C．拉弗曲线

D．瓦尔拉斯曲线

半夏的气味是

A．气微辛，味苦

B．气微，味淡

C．无臭，味辛辣，麻舌而刺喉

D．气芳香，味辛辣

E．气微香，味苦涩

When I stepped out the plane from Miami into Charlotte, North Carolina, airport for a connecting flight home, I immediately knew something was wrong. Lots of desperate people crowded the terminal. I quickly learned that flights headed to the Northeast were called off because of a storm. The earliest they could get us out of Charlotte was Tuesday. It was Friday. A gate agent stood on the counter and shouted, “Don’t ask us for help! We cannot help you!”

I joined a crowd that ran from terminal to terminal in search of a flight out. Eventually, I found six strangers willing to rent a van with me. We drove through the night to Washington, where I took a train the rest of the way to Providence.

The real problem, of course, is that incidents like this happen every day, to everyone who flies, more and more often. It really gets to me, though, because for eight years I was on the other side, as a flight attendant for Trans-World Airlines (TWA).

I know the days are gone when attendants could be written up if we did not put the lines napkins with the TWA logo in the lower right-hand corner of the first-class diners’ trays. As are the days when there were three dinner options on flights from Boston to Los Angeles in economy class. When, once, stuck on a tarmac（机场停机坪）in Newark for four hours, a planeload of passengers got McDonald’s hamburgers and fries by thoughtfulness of the airline. I have experienced the decline of service along with the rest of the flying public. But I believe everything will change little by little, because I remember the days when to fly was to soar (翱翔). The airlines, and their employees, took pride in how their passengers were treated. And I think the days are sure to come back one day in the near future.

小题1:Many people crowded the terminal because _______.

A．they were ready to board on the planes

B．something was wrong with the terminal

C．the flights to the Northeast were canceled

D．the gate agent wouldn’t help the passengers小题2: How did the writer get to Providence at last?___

A．by air

B．by van

C．by train

D．by underground小题3:Which of the following is NOT true according to the passage?______

A．Incidents happened to those who fly quite often.

B．The writer used to be a flight attendant for Trans-World Airlines.

C．Even a small mistake might cause complaints from passengers in the past.

D．McDonald’s hamburgers and fries were among regular dinner options.小题4:What can be implied from the passage?____

A．The writer lived in Charlotte, North Carolina.

B．The writer thought the service was not as good as it used to be.

C．The writer with other passengers waited to be picked up patiently.

D．Passengers would feel proud of how they were treated on the plane.

X、Y、Z均是由两种短周期元素组成的无机物，它们的每个分子中均含有l8个电子，相关信息如下表所示(“／”表示相应的信息略去)：

回答下列问题：

（1）X常用作火箭推进剂，其分子的球棍模型为，则X的化学式为    .

（2）Y的化学性质描述正确的是   。

a．不稳定性    b．弱碱性    c．氧化性 d．还原性

（3）Z的化学式可用H₂A表示。将一定量的Z气体通入0．05mol·L^-1CuSO₄溶液中，二者恰好完全反应。已知Ksp(CuA)=6．0×10^-36。若不考虑溶液体积的变化，则：

①反应后溶液的pH=     。

②若反应后溶液中c(A^2-)=2．0×10^-30mol·L^-1，则溶液中c(Cu²⁺)= mol·L^-1。

（4）将一定量的Z气体通人NaOH溶液中，在所得溶液中逐滴加入稀盐酸至过量，产生的气体与HCl的物质的量的关系如图所示(忽略气体的溶解和HCl的挥发)。

①O点溶液中所含溶质的化学式为     。

②已知a点溶液呈碱性，该溶液中离子的物质的量浓度由大到小的顺序是      。