光纤的衰减窗口中，传输损耗最小的窗口为（）。 A.850nm B.1310nm C.

设等比数列{a_n}的公比q＜1，前n项和为S_n，已知a₃=2，S₄=5S₂，求{a_n}的通项公式。

男，35岁。出现反复发热伴双下肢溃烂半年，入院后做培养发现是孢子菌。追问病史有嫖娼史。

下一步应做什么检查 （）

A.血糖

B.抗-HIV抗体测定

C.X线胸片

D.病理活检

E.血尿常规

现有四组混合物分离实验：①从氯化钠溶液中提纯氯化钠②从汽油和氯化钠溶液的混合液提纯汽油③从40%的乙醇溶液提纯乙醇 ④从碘水中提纯碘单质，正确的操作方法依次是(    )

A．蒸发、蒸发、蒸馏、分液

B．蒸发、萃取、分液、蒸馏

C．蒸发、分液、蒸馏、萃取

D．萃取、蒸发、分液、蒸馏

The Winter Olympics is also called the White Olympics. At this time, many colorful stamps are published to mark the great Games. The first stamps marking the opening came out on January 25, 1932 in the United States for the 3rd White Olympics. From then on, publishing stamps during the White Olympics became a rule.

During the 4th Winter Olympic Games a group of stamps were published in Germany in November 1936. The five rings of Olympics were drawn on the front of the sportswear. It was the first time that the rings had appeared on the stamps of the White Olympics.

In the 1950’s, the stamps of this kind became more colorful. When the White Olympics came, the host countries as well as the non-host countries published stamps to mark those Games. China also published four stamps in February 1980, when the Chinese sports men began to take part in the White Olympics.

Japan is the only Asian country that has ever held the White Olympics. Altogether 14,500 million stamps were sold to raise money for this sports meet.

Different kinds of sports were drawn on these small stamps. People can enjoy the beauty of the wonderful movements of some sportsmen.

小题1: We can infer from the passage that ______.

A．No stamps were printed in the first two White Olympics

B．The first stamps marking the opening came out for the 3^rd White Olympics

C．The 3^rd White Olympics was in the USA

D．The 3^rd White Olympics were held in 1932小题2: The world made it a rule to publish stamps to mark the great world games _____.

A．after the year 1936

B．after the 3rd White Olympics

C．before the 3rd White Olympics

D．before the year 1932小题3: The Winter Olympics is held once _______.

A．every two years

B．every three years

C．every four years

D．every five years小题4:Which of the following is TRUE?

A．Only the host countries can publish stamps to mark those Games.

B．Only the non-host countries can publish stamps to mark those Games.

C．All the countries can publish stamps to mark those Games.

D．Japan can’t publish stamps to mark those Games小题5: What may appear on the stamps of the White Olympics?

A．Basketball.

B．Table tennis.

C．Football.

D．Skating.

对于大城市郊区的住宅，当降低或取消连接它与市区的高速公路收费时，消费者对其需求就会增加。（）