A:大量食用纯碱可使钙离子沉淀完全,预防胆结石产生
B:不食用含钙的食品
C:适量服用维生素E、维生素C等抗氧化自由基可预防胆结石
D:手术切除胆囊
直线l交抛物线y2=2x于A、B两点,且OA⊥OB,则直线l过定点( )
过直线外一点,可以画无数条直线和已知直线垂直.
根据句意,用括号内所给单词的适当形式填空(1)A glass is used for ____ (drink) water.(2)What is the most ____ (use) invention in the world?(3)Do you know the ____ (heat) ice cream scoop?(4)This kind of bicycle was____ (invent) by a middle school student.(5)What do you think of these ____ (invent)?
通常情况下,下列现象不会发生的是( )