【单选题】Down 综合征属于染色体畸变中的( )
【单选题】Compared to the last version, this product may have been an improvement, but its sales _______ is still a mystery.
【单选题】设A 1 、A 2 、A 3 表示3个事件,则A1A2+A1A3+A2A3表示( ).
【单选题】设A1,A2,A3为三个随机事件,用A1,A2,A3表示事件“A1,A21,A3不都发生”的表示式为( ).
【简答题】This product may ( 包含)______ milk and eggs.
【单选题】This product may _______ milk and eggs.