What ______ when the earthquake happened on May 12th.
A：are you doing
B：were you doing
C：do you do
D：did you do
由于一直吃精面馒头很少吃粗粮等不合理的饮食结构，某同学患上脚气病，这说明他体内长期缺乏（ ）
从气候类型看，几乎都属于寒带冰原气候类型的是 ____ 洲．
