A：must have climbed
B：was able to clim
C：could have climbed
D：should have climbed
陆生动物对环境的变化有许多形式的适应，这是因为（ ）
如果你生活在北宋时期，你不可能经历的事情是（ ）
It's the third day of the week. It's________.
