已知:二次函数y=x2+2ax﹣2b+1和y=﹣x2+(a﹣3)x+b2﹣1的图象都经过x轴上两个不同的点M,N,则a=( ),b=( )。
1;2
构造柱和圈梁的设置主要是为了( )。
A.提高建筑物的整体性,抵抗地震力
B.承受竖向荷载
C.便于砌筑墙体
D.建筑构造的需要
A researcher found that, in proportion to their body weights, children eat more carbohydrates than adults do. Children also exercise more than adults do. The researcher hypothesized that carbohydrate consumption varies in direct proportion to the calorie demands associated with different levels of exercise. Which of the following, if true, most seriously undermines the researcher’s hypothesis
A.More carbohydrates are eaten per capita in nations where the government spends more per capita on public exercise programs.
B.Children who do not participate in organized sports tend to eat fewer carbohydrates than children who participate in organized sports.
C.Consumption of increased amounts of carbohydrates is a popular tactic of runners preparing for long-distance races.
D.Periods of physical growth require a relatively higher level of carbohydrate consumption than otherwise.
E.(E) Though carbohydrates are necessary for the maintenance of good health, people who consume more carbohydrates are not necessarily healthier.