下列关于一株大豆和一条鲫鱼的叙述,错误的是( )
A:都由一个细胞﹣﹣受精卵发育而来
B:其细胞都具有的基本结构是细胞膜、细胞质、细胞核
C:其细胞内都具有的能量转换器是线粒体
D:大豆的叶、鲫鱼的鳃都属于组织
用两把刻度尺测量同一物体的长度,如图所示.利用A刻度尺测得物体长为____ cm,利用B刻度尺测得物体长为____cm,造成结果不同的原因是____不同。
End of Term Report
Student's name
Zhang Xing
Subject
English
Teacher
Mr. Dickens
At the beginning of this term
He found that studying English was very ____
In writing
His ____is better.
In speaking
He can have English ____with his friends and with me.
He can answer my questions in English____.
Next term
If he ____like this, he will do much better.
已知圆x2+y2﹣4ax+2by+b2=0(a>0,b>0)关于直线x﹣y﹣1=0对称,则ab的最大值为( )
①讲究家庭秩序,事事请妈妈做主 ②关心体贴妈妈,从点滴小事做起
③分担应尽的责任,学会帮助妈妈 ④尊重理解妈妈,调试逆反心理
下列各项措施中,有利于生态系统稳定的是( )