一个自由下落的物体，前3s内下落的距离是第1s内下落距离的[ ]
A.2倍
B.3倍
C.6倍
D.9倍
答案：D
小剂量亚甲蓝治疗（）
A.有机磷中毒
B.铅中毒
C.氰化物中毒
D.亚硝酸盐中毒
E.急性酒精中毒
Look，read and answer. (看图，回答问题)
1. Did you visit your grandparents last weekend?
____________________________________
2. What did you do last Sunday?
3. What did they do last Saturday?
