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:
“鸠占鹊巢”说明“鸠”在生殖和发育过程中没有经历的阶段是( )
下列成语使用有错误的一项是( )。
某同学静止站在磅秤上,在下列几对力中,哪一对是平衡力( )
____(凝视,盯着看)at people is considered rude in Britain and young children will be scolded by their parents if they look too long at another person.