It's very important ______ us ______ hard.
A:for; to study
B:of; to studying
C:for; studying
D:of; to study
已知函数fx=x2-6,若a<b<0,且fa=fb,则a2b的最小值是( )
慌张(huāng) 忠实(zōng) 鸣叫(mín)
毕竟(jìng) 垂下(chuí) 饮水(yǐng)
请用所学化学知识解释下列事实:
(1)洗涤剂能除去油污,是因为它具有 ____功能.
(2)金秋时节,古城开封处处都能闻到怡人的菊花香气 ____.
(3)镁条在空气中燃烧后,生成物的质量比原来镁条的质量增大 ____.
(4)牛奶在夏天比冬天更容易变酸 ____.