[单选题]在电场中，正电荷受电场力的作用总是（ ）移动。
A.从低电位向高电位
B.从高电位向低电位
C.保持原位
D.垂直于电力线的方向

The modern urban planning and redevelopment movement (1) in response to the (2) and dirtiness of the slum areas which were (3) by the Industrial Revolution in the 19th century. Reformation of these areas (4) the objective of early city planners, who imposed regulatory laws establishing (5) for (6) , sanitation, water supply, sewage and public health conditions. Urban planners also introduced parks and playgrounds into crowded city neighborhoods, (7) places for recreation, as well as (8) relief.
The chief new urban-planning concept of the early 20th century was zoning—the regulation of building activity to set (9) of height and (10) and to protect established neighborhoods.
Urban territory (11) as a result of improved public transportation. Workers could live far from their jobs, traveling back and forth by bus, subway, or car.
By the middle of the 20th c
A. housing
B. house
C. home
D. family

Most children with healthy appetites are ready to eat almost anything that is offered them and a child rarely dislikes food (36) it is badly cooked. The (37) a meal is cooked and served is most important and an (38) served meal will often improve a child’s appetite. Never ask a child (39) he likes or dislikes a food and never (40) likes and dislikes in front of him or allow (41) else to do so. If the father says he hates fat meat or the mother (42) vegetables in the child’s hearing he is (43) to copy this procedure. Take it (44) granted that he likes everything and he probably (45) , Nothing healthful should be omitted from the meal because of a (46) dislike. At meal times it is a good (47) to give a child a small portion and let him (48) back for a second helping rather than give him as (49) as he is likely to eat all at once. Do not talk too much to the child (50) <
A. or
B. nor
C. but
D. neither