同一地区上下地层在沉积层序上是连续的，产状一致，如图所示。P与T地层之间是（）。 A

Can dolphins talk? Maybe they can’t talk with words, but they talk with sounds. They show their feelings with sounds.

Dolphins travel in a group. We call a group of fish a “school”. They don’t study, but they travel together.

Dolphins are mammals（哺乳动物）, not fish, but they swim together in a school. Dolphins talk to the other dolphins in the school. They give information. They tell when they are happy or sad or afraid. They say“welcome”when a dolphin comes back to the school. They talk when they play.

They make a few sounds above water. They make many more sounds under water. People can’t hear these sounds because they are very, very high. Scientists make tapes of the sounds and study them.

Sometimes people catch a dolphin for a large aquarium.(An aquarium is a zoo for fish.) People can watch the dolphins in a show. Dolphins don’t like to be away from their school in an aquarium. They are sad and lonely.

There are many stories about dolphins. They help people. Sometimes they save somebody’s life. Dolphin meat is good, but people don’t like to kill them. They say that dolphins bring good luck. Many people believe this.

小题1:A school of dolphins means_____.

A．a zoo for dolphins

B．a show by dolphins

C．a group of dolphins

D．a library of dolphins小题2: A dolphin feels _____in an aquarium.

A．afraid

B．happy with people watching them

C．lucky

D．sad and lonely小题3:Which sentence is true?

A．Dolphins talk with words.

B．Dolphins always bring good luck.

C．Dolphins make more sounds above water.

D．Dolphins can’t breathe（呼吸） under the water.小题4:People can’t hear the dolphins’ sounds because they are         .

A．low

B．high

C．soft

D．quiet小题5:From the passage we know_____.

A．Dolphins travel together.

B．Dolphins talk with words when they play.

C．Dolphins like to live in aquariums.

D．All people want to catch dolphins and eat them.

己知25mL 0.1mol/L Na₂S₂O₃溶液恰好把224mL Cl₂（标准状况）完全反应为Cl^-，则S₂O₃^2-将转化为（　　）

A．S^2-

B．S

C．SO₃^2-

D．SO₄^2-

已知 25℃时有关弱酸的电离平衡常数：

则下列说法正确的是（   ）

A．等物质的量浓度的各溶液 pH 关系为：pH ( NaCN)＞pH(Na₂CO­₃)＞pH( CH₃COONa)

B．浓度均为0.2mol/LNaHCO₃和 Na₂CO₃溶液中，存在的粒子种类不相同

C．0.4 mol·L^－1HCN 溶液与 0.2 mol·L^－1NaOH 溶液等体积混合后，所得溶液中：c(Na⁺)＞c(OH^－)＞c(H⁺)

D．25℃时，pH＝4且浓度均为0.1 mol·L^－1的 CH₃COOH、CH₃COONa混合溶液中：

c(Na⁺)＋c(H⁺)＞c(CH₃COO^－)＋c(CH₃COOH)

已知数列{an}中，a1=1，a1+2a2+3a3+…+nan= n+1 2 an+1(n≥1，n∈Z)． （1）求数列{an}的通项公式an； （2）求数列{n2an}的前n项和Tn； （3）若存在n∈N*，使关于n的不等式an≤（n+1）λ成立，求常数λ的最小值．

患者男，65岁，食管中段鳞癌，既往30年前因"胃溃疡"行"胃大部切除术"，合理的治疗方案为（）

A.食管癌切除，食管、空肠弓上吻合术

B.食管癌切除，食管、食管弓上吻合术

C.食管癌切除，结肠间置代食管术

D.食管癌切除，人造食管间置术

E.食管癌切除，颈部食管旷置，永久胃造瘘术