题目内容：
阅读下文，回答题。Migrant Workers
In the past twenty years， there has been an increasing tendency for workers to move from one country to another. 1 some newly independent countries have understandably restricted most jobs to local people， others have attracted and welcomed migrant workers. This is particularly the case in the Middle East, 2 increased oil incomes have enabled many countries to 3 outsiders to improve local facilities. 4 the Middle East has attracted oil-workers from the USA and Europe. It has brought in construction workers and technicians from many countries， 5 South Korea and Japan.
In view of the difficult living and working conditions in the Middle East， it is not 6 that the pay is high to attract suitable workers. Many engineers and technicians can earn at least
7 money in the Middle East as they can in their own country， and this is a major attraction. An allied benefit is the low taxation or complete lack of it. This increases the net amount of pay received by visiting workers and is very popular with them. Sometimes a disadvantage has a compensating advantage. 8 ， the difficult living conditions often lead to increased friendship when workers have to depend on each other 9 safety and comfort. 10 ， many migrant workers can save large sums of money partly 11 the lack of entertainment facilities. The work is often complex and full of problems but this merely presents greater challenge to engineers who prefer to find solutions 12 problems rather than do routine work in their home country.
One major problem which 13 migrant workers in the Middle East is that their jobs are temporary ones. They are nearly always on contract， so it is not easy for them to plan ahead with great confidence. This is to be expected since no country welcomes a large number of foreign workers as permanent residents. 14 ， migrant workers accept this disadvantage， along with others， because of the 15 financial benefits which they receive.
请在1处填写正确答案。 A． As
B． Since
C．While
D． Although
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