instruction:
This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.
question:
The city remained in the hands of Christian troops until 1102, when the Almoravids retook the city and restored the Muslim religion. Although the self-styled 'Emperor of All Spain', Alfonso VI of León and Castile, drove them from the city, he was not strong enough to hold it. The Christians set it afire before abandoning it, and the Almoravid Masdali took possession on 5 May 1109. The event was commemorated in a poem by Ibn Khafaja in which he thanked Yusuf ibn Tashfin for the city's liberation.The declining power of the Almoravids coincided with the rise of a new dynasty in North Africa, the Almohads, who seized control of the peninsula from the year 1145, although their entry into Valencia was deterred by Ibn Mardanis, King of Valencia and Murcia until 1171, at which time the city finally fell to the North Africans. The two Muslim dynasties would rule Valencia for more than a century.
answer:
In what year did Christian troops lose control of Valencia?


question:
Although the existence of dictionaries and encyclopedias spanned into ancient times, the texts changed from simply defining words in a long running list to far more detailed discussions of those words in 18th-century encyclopedic dictionaries. The works were part of an Enlightenment movement to systematize knowledge and provide education to a wider audience than the elite. As the 18th century progressed, the content of encyclopedias also changed according to readers' tastes. Volumes tended to focus more strongly on secular affairs, particularly science and technology, rather than matters of theology.
answer:
How did dictionaries and encyclopedias change in the 18th century?


question:
Jehovah's Witnesses are perhaps best known for their efforts to spread their beliefs, most notably by visiting people from house to house, distributing literature published by the Watch Tower Society in 700 languages. The objective is to start a regular "Bible study" with any person who is not already a member, with the intention that the student be baptized as a member of the group; Witnesses are advised to consider discontinuing Bible studies with students who show no interest in becoming members. Witnesses are taught they are under a biblical command to engage in public preaching. They are instructed to devote as much time as possible to their ministry and are required to submit an individual monthly "Field Service Report". Baptized members who fail to report a month of preaching are termed "irregular" and may be counseled by elders; those who do not submit reports for six consecutive months are termed "inactive".
answer:

What are Jehovah Witnesses probably best known for by outsiders?