水泵在吸水时,利用大气压力,通过()运动,在水泵膛内和吸水管内造成真空或负压,把水吸入泵内并输送出去。
(A)水流
(B)机械
(C)水泵旋转
(D)车轮
参考答案:B
有机物分子中原子(或原子团)间的相互影响会导致化学性质的不同。下列叙述不能说明上述观点的是
A.苯酚能与NaOH溶液反应,而乙醇不行
D.相同物质的量的甘油和乙醇分别与足量金属钠反应,甘油产生的H2多
Traditionally, the woman has held a low position in marriage partnerships. While her husband went his way, she had to wash, stitch and sew. Today the move is to liberate the woman, which may in the end strengthen the marriage union. Perhaps the greatest obstacle to friendship in marriage is the amount a couple usually sees of each other. Friendship in its usual sense is not tested by the strain of daily, year-long cohabitation. (46) Couples need to take up separate interests (and friendship) as well as mutually shared ones, if they are not to get used to the more attractive elements of each other’s personalities. (47) Married couples are likely to exert themselves for guests--being amusing, discussing with passion and point--and then to fall into dull exhausted silence when the guests have gone. As in all friendship, a husband and wife must try to interest each other, and to spend sufficient time sharing absorbing activities to give-them continuing common interests, (48) But at the same time they must spend enough time on separate interests with separate people to preserve and develop their separate personalities and keep their relationship fresh. (49) For too many highly intelligent working women, home represents chore obligations, because the husband only tolerates her work and does not participate in household chores. For too many highly intelligent working men, home represents dullness and complaints--from an over-dependent wife who will not gather courage to make their own life. In such an atmosphere, the partners grow further and further apart, both love and liking disappearing. (50) For too many couples with children, the children are allowed to command all time and attention, allowing the couple no time to develop liking and friendship, as well as love, allotting exclusive parental roles.