水稻育秧期间,如长期水淹,会导致烂种烂秧,其原因是
A:细胞吸水过多
B:细胞缺氧,呼吸停止
C:细胞无氧呼吸产生乳酸中毒
D:细胞无氧呼吸产生酒精中毒
如图,已知长方形ABCD,R,P分别是DC,BC上的点,E,F分别是AP,RP的中点,当点P在BC上从点B向点C移动,而点R不动时,那么下列结论成立的是( )
已知:①BrR1 →THFMg BrMgR1 →BrR2 R1﹣R2(THF为一种有机溶剂)
②C6H5﹣O﹣R ①Li,THF,室温②H3O+ C6H5﹣OH
请回答下列问题:
Hello,I'm Fangfang. I'm 10. My favourite letter is A. Yellow is my favourite colour. This is Sam. The ABC song is his favourite song. His favourite colour is blue. D is his favourite letter.
鲨鱼属于“鱼纲”,鲸鱼属于“哺乳纲”,下列特征中哪项是把它们分开的主要依据之一( )