设离散型随机变量X服从参数λ=2的泊松分布，则随机变量2X的方差D（2X）=（）。

根据短文内容，从题中所给的A、B、C、D四个选项中，选择最佳答案。

Little Tommy was doing very badly in math. His parents had tried everything—tutors (家庭教师), cards, special learning centers—in short, everything they could think of. Finally they took Tommy to a catholic (天主教的) school.

After the first day, little Tommy came home with a very serious look on his face. He didn’t kiss his mother hello. Instead, he went straight to his room and started studying. Books and papers were spread out all over the room and little Tommy was hard at work. His mother was surprised. She called him down to dinner .And as soon as he finished eating，he went back to his room without a word. In no time he was back hitting the books again. This went on for some time, day after day while the mother tried to understand what was happening.

Finally, little Tommy brought home his report card. He quietly put it on the table and went up to his room and hit the books. His mom looked at it and to her surprise, little Tommy got an “A” in math. She could no longer hold her curiosity (好奇心). She went to his room and asked, “What made you make such great progress ? Was it the nuns (修女)?”

Little Tommy looked at her and shook his head, “No. ”

“Well then,” she asked again. “What was it?”

Little Tommy looked at her and said, “Well, on the first day of school, when I saw that man nailed (钉) to the plus sign (十字架), I knew they weren’t joking. ”

小题1:Why did Tommy’s parents send him to a catholic school?

A．Because he could eat well there.

B．Because he could earn more about nuns.

C．Because his parents wanted him to do better in his math.

D．Because his parents didn’t want him to learn math any more.小题2:Tommy’s mother felt surprised that his son _______.

A．was still the same as usual

B．ate so much at dinner

C．kissed her hello after school

D．worked hard but said little小题3:“Hitting the books” means “_______” in Chinese.

A．用功

B．捶书

C．发泄

D．振作小题4:The last sentence in the passage shows that _______.

A．Tommy felt sorry for the nail

B．Tommy was afraid of being nailed

C．Tommy didn’t like the plus sign

D．Tommy liked playing jokes on others小题5:From the passage, we can infer (推断) that _______.

A．we should be strict with ourselves

B．mistaking (误解) might do good sometimes

C．a catholic school is better than other ones

D．nuns are good at helping children with their math

关于恒生指数的叙述，正确的是（）。

A．恒生指数是由香港恒生银行于1969年11月24日起编制公布、系统反映香港股票市场行情变动最有代表性和影响最大的指数

B．它挑选了33种有代表洼的上市股票为成分股用加权平均法：十算

C．恒生指数具有基期选择恰当、成分股代表性强、计算频率高、指数连续性好等特点

D．恒生指数于2006年2月提出改制，首次将股纳入恒生指数成分股

若x+y=5，xy=1，则2x²+2y²-10=______．

4，5，11，14，18，23，25，( )

A．28
B．30
C．32
D．34

将输液装置的暴露端连接到同一装置另一接口形成回路的做法是正确的。