—Tom wants to know if you _______ a picnic next Sunday
—Yes. But if it __________ , we’ll visit the museum instead
A:will have ; will rain
B:have ; rains
C:have ; will rain
D:will have ; rains
在下列各图中,每个图的两个变量具有相关关系的图是 ( )
20910000000≈____亿
1597000000≈____亿