式子x-4是二次根式的条件是______．

Henry works in a factory. He comes from a poor family and was in school for only four years. He has to do the hard work, but he is paid less. He likes to watch football matches very much and spends much time on them.

One afternoon there was a big football match on the playground. He borrowed some money from his friend and hurried there. There were a lot of people there. And all the tickets were sold out. He was sorry for it. He saw a pole（杆子）outside the playground and climbed it quickly. A policeman came and said, “It is dangerous to stay on it! Come down!”

“Wait a minute, please!” Henry said and just at that moment the policeman heard cheers on the playground and asked in a hurry, “Which team has kicked a goal（进球）?” “Ours!” “Wonderful! You can stay there. But take care!” The policeman said happily and left. When the match would be soon over, he came back again and asked, “Who has won?” “Theirs, 3:2.” “Come down,” the policeman said angrily. “Such a match is not worth watching!”

Henry had to come down. But soon they heard cheers again. The policeman said in a hurry, “Climb up quickly and see who has kicked a goal.”

小题1:From the passage we know that ____________.

A．Henry doesn’t like his work

B．Henry comes from a rich family

C．Henry doesn’t like the policeman

D．Henry is paid less小题2:Henry failed to get a ticket for the match that day because __________.

A．he had no money to buy a ticket

B．he didn’t want to buy a ticket

C．he had no time to buy a ticket

D．all the tickets were sold out小题3:The policeman asked Henry to come down the pole at first because __________.

A．it was dangerous

B．Henry had no ticket

C．their team kicked a goal

D．the other team kicked a goal小题4: From the third paragraph（段落）, we can guess that __________.

A．the policeman wanted to teach Henry a lesson

B．the policeman tried to please Henry

C．the policeman didn’t like Henry

D．the policeman was also a football fan小题5:The policeman asked Henry to climb up the pole __________.

A．to cheer for their team

B．to see the result of the match

C．to cheer for the other team

D．to say goodbye to their team

关于实际碳酸氢根，正确的叙述是（）

A.为未排除呼吸因素的代谢因素

B.为排除了呼吸因素的代谢因素

C.为未排除代谢因素的呼吸因素

D.为排除了代谢因素的呼吸因素

E.为代谢和呼吸的共同因素

下列行为中，海关可处以1000元以上5000元以下罚款的有( )。

A．报关单位未向海关备案，擅自变更“报关专用章”

B．报关单位向海关工作人员行贿

C．报关单位非法代理他人报关

D．报关单位的法定代表人发生变更，未按照规定向海关办理变更手续

帧中继的设计主要是以广域网互连为目标。

工作中哪些现象可判断安全阀出现了故障？