单项选择题
遗传变异和表观遗传变异可以共同作用维持生殖隔离，避免物种的融合。（ ）
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相关考题
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未知题型
做一件事，往往有利也有弊，只有利而无弊的事情几乎是没有的。《淮南子．人间训》云：“众人皆知利利而病病，惟圣人知病之为利，利之为病也。”看来古人已经注意到利弊的辩证关系。 下列表述符合文意的是( )。A.现实生活中的事情都由利与弊组成B.要善于分析，争取做到利大于弊C.利与弊不是绝对的，是可以转化的D.我们应当努力争取做到有利无弊
A.人间训》云：“众人皆知利利而病病，惟圣人知病之为利，利之为病也。”看来古人已经注意到利弊的辩证关系。
B.现实生活中的事情都由利与弊组成
B.要善于分析，争取做到利大于弊
C.利与弊不是绝对的，是可以转化的 -
判断题
叉车载物行驶在坡度超过7°和高于一档的速度上下坡时非特殊情况不得使用制动器。 正确 错误 -
未知题型
In the United States, the first day-nursery was opened in 1854. Nurseries were established in various areas during the (1)_____ half of the 19th century; most of (2)_____ were charitablE.Both in Europe and in the U.S. the day nursery movement received great (3)_____ during the First World War, when (4)_____ of manpower caused the industrial employment of unprecedented numbers of women.In some European countries nurseries were established (5)_____ in munitions plants, under direct government sponsorship. (6)_____ the number of nurseries in the U.S. also rose (7)_____, this rise was accomplished without government aid of any kinD.During the years following the First World War, (8)_____, Federal, State, and local governments gradually began to exercise a measure of control (9)_____ the day-nurseries, chiefly by (10)_____ them and by inspecting and regulating the conditions within the nurseries.The (11)_____ of the Second World War was quickly followed by an increase in the number of day-nurseries in almost all countries, ms women were (12)_____ called upon to replace men in the factories.On this (13)_____ the U.S. government immediately supported the nursery schools, (14)_____ $6,000,000 in July, 1942 for a nursery-school program for the children of working mothers.Many States and local communities (15)_____ this Federal aiD.By the end of the war, in August, 1945, more than 100,000 children were being cared (16)_____ in daycare centers receiving Federal (17)_____. Soon afterward, the Federal government (18)_____ cut down its expenditures for this purpose and later (19)_____ them, causing a sharp drop in the number of nursery schools in operation. However, the expectation that most employed mothers would leave their (20)_____ at the end of the war was only partly fulfilleD.A.latterB.lateC.otherD.first
A.S.
B.
C.S.
D.
E.
F.S.
G.
H.
A.latter
B.late
C.other
