We are glad to hear that the terrorists ________ by the brave policemen several days ago.
A:are caught
B:were caught
C:have been caught
D:are going to be caught
一对夫妇近亲结婚,两人的表现型正常,但生了一个患白化病的孩子.他们若再生一个孩子,患白化病的可能性是( )
已知三棱锥S-ABC的所有顶点都在球O的球面上,SA⊥平面ABC,SA=23,AB=1,AC=2,∠BAC=60°,则球O的表面积为( )
了解必要的用药知识和急救技能,对于保障身体健康,挽救生命具有重要意义,下列有关说法正确的是( )
规定:当产品中的此种元素含量满足≥18毫克时,该产品为优等品.