下图表示的是身边一些物质在常温下的近似pH,有关这些物质的比较和判断正确的是()
A:柠檬的酸性比橘子弱
B:橘子汁显碱性
C:草木灰水的碱性最强
D:萝卜显中性
有学者认为:中国古代科技固然成绩突出,但“这些成果技术方面停滞于农业和手工业的经验工艺的水平上,在理论上始终贯穿着天人合一的思想,以变幻莫测的道、气等概念来建构学术体系,……混有大量的荒诞不经的反科学的成份。”这主要表明中国古代科技( )
在平面直角坐标系中,已知A(1,0),B(0,﹣1),P是曲线y= 1−x2 上一个动点,则 BP→ • BA→ 的取值范围是____.
She looked at his fingers with wonder as they turned each page and suddenly reached for his hand. She was amazed by his and the softness and warmth of his skin.
抛物线y=(x+2)2-3可以由抛物线y=x2平移得到,则下列平移过程正确的是( )