A:性状分离:杂种后代中,同时出现显性性状和隐性性状的现象
B:伴性遗传:由位于性染色体上的基因控制,遗传上总是与性别相关联的现象
C:显性性状:两个亲本杂交,子一代中显现出来的性状
D:等位基因:位于同源染色体的相同位置上,控制相对性状的基因
B组:空间存在一匀强磁场B,其方向垂直纸面向里,另有一个点电荷+Q的电场,如图所示,一带电﹣q的粒子以初速度v0从某处垂直电场、磁场入射,初位置到点电荷的距离为r,则粒子在电磁场中的运动轨迹可能为( )
看书一小时后,向远处眺望一会儿,可以预防近视眼,主要原因是 ( )
⑴Mom and Dad are the most important people in your life. They have been looking after you since you were born. ⑵你应该一直爱他们。You should also get on well with them. But some children don't know how to do this. Here are some ways to help you. Spend more time with your parents. ⑶Don't spend too much time playing computer games or watching TV. Ask your parents to play with you. ⑷和他们交谈或者散步。 Be kind to your parents. You can make them happy with a smile when you come home. You can send your mother a card on Mother's Day or tell your father a joke on his birthday. ⑸You can also clean your room by yourself. Work hard. If you do your best in your studies, your parents will be proud of you.
方程组4x+3m=28x-3y=m的解x、y满足x>y,则m的取值范围是( )