用³²P标记的噬菌体侵染大肠杆菌，经培养、搅拌、离心、检测，上清液的放射性占15%，沉淀物的放射性占85%。上清液带有放射性的原因可能是（   ）

    The Chongyang Festival falls on the ninth day of the ninth lunar month and is also called the Double Ninth Festival. As both the month and the day are nine, it got this name. To celebrate the day, people usually climb mountains and enjoy chrysanthemum (菊花), so the festival is also known as the Height Ascending (登高) Festival or the Chrysanthemum Festival. In China, nine has the similar pronunciation with the word “forever”, meaning long life. So the Chinese government set the day as the Seniors' Day.

    The festival has a history of over 2000 years. During the Warring States Period, there was the Chongyang Festival. But it was only celebrated in the imperial palace. From the Han Dynasty, it began to be popular among the common people. The name of the Chongyang Festival first appeared in the Three Kingdoms Period. During the Jin Dynasty, there were customs of enjoying chrysanthemum and drinking wines on the day. It was not (A) officially set as a festival until the Tang Dynasty. Since then, all the people have spent the festival with kinds of activities. In the Ming and Qing Dynasties, people in the imperial palace all ate flower cakes to celebrate. The emperor climbed the mountain on the day as well. In 1989, the Chinese government set the day as the Seniors' Day.

    As September has the clear sky and fresh air, it is a very good time to climb the mountain. There will be a happy sense of excitement by climbing the mountain in this season. Also, it is good for health. Since the Western Han Dynasty, it has been the custom of climbing on the Chongyang Festival.

    On the day, enjoying chrysanthemum is very popular as the flower means long life. Drinking chrysanthemum is regarded as a way to prevent disasters and bad things. Inserting Zhuyu and sticking chrysanthemum are also traditions to avoid the bad as (B) they have special smells which can repel (驱逐) insects and keep out the cold.

    Eating Chongyang cakes is another tradition on the festival. There is no fixed way of the cake but the one with nine layers (层) with two sheep on it is the best. Two sheep means Chongyang. Nine layers show people could do well in everything.

读“东北地区示意图”，完成下列内容。

    A businessman, with a lot of money, was walking through a remote(偏远的) area. Upon1 this, a thief followed him, planning to2 his money at a certain time. The businessman(商人) noticed something was 3 and he started to pay much more 4to the thief.

    The businessman asked the thief if he5help find some water nearby, and when the thief went to6 the water, the businessman put all of his7into the thief's bag. Then the thief returned and told the businessman8the water was.9the businessman left to get some water, the thief quickly 10 the businessman's bag. Certainly, there was nothing that the thief 11

    The thief was12 but he still did not give up hope. After some time, the businessman returned and they both 13for a long time. Then the businessman got tired and 14 under a big tree. The thief again checked the businessman's bag and still did not find any money. So the thief 15 that the businessman did not actually have any money with him.

    Finally, they arrived at a city. When the thief went after a job and left his own bag behind, the businessman 16 in and took back all of his own money he had put there17When the thief came back, he was surprised to see that the businessman was 18some jewels with the money in his bag. The thief couldn't 19asking the question, “I didn't know you had money on the 20.” The businessman smiled to him, “Of course you didn't, because it is not yours.”