给水管道与市政管道界线是以()为界。

传统点火系中的点火线圈的作用是()

A.按顺序向各气缸点火
B.将低压电转变为高压电
C.接通或断开点火系一次电路
D.用来减小断电器触头断开时的火花

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Couples are restricting the size of their families in the UK because of cash worries brought on by the financial crisis and the subsequent decline. Were now up to nearly 3. 7 million families where there is an only child, a rise from about 3. 3 million in 2005. That means nearly half of all parents have only one child. Financial worries arent the only driver. The trend towards later motherhood has been mentioned as a cause, as have soaring costs of raising a child, which have been calculated as ￡ 222, 500 from birth to 21 years of age. This is an increase of nearly 40% in 10 years. The increasing availability of IVF(试管婴儿)is also a factor and an interesting one. Couples who might have remained childless in the past now invest in IVF and get pregnant. And because of the cost they stop after one child. It may not be a bad thing: there are outstanding examples of talented only children. Some argue that being an only child promoted their success. These include actors Natalie Portman and Al Paci-no, golfer Tiger Woods and even Queen Victoria. A study from the Institute for Social and Economic Research at the University of Essex also showed that the fewer brothers and sisters a child has, the happier they are. It seems fighting for parental attention and affection—which sometimes descends into physical fights—is more stressful than any adult had previously thought. And its not compensated(弥补)by having a playmate.The smaller size of UK families is mainly related to______.

A．financial
C.technical
D.health
E.cultural

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