过抛物线C：y²=4x的焦点F作直线l将抛物线C于A、B，若|AF|=4|BF|，则直线l的斜率是____．

图一为人体消化系统部分形态结构示意图，图二为淀粉、蛋白质、脂肪在消化道各部分被消化程度的示意图，请据图回答：

Smoking is bad for your health. You'd better _______.

① What’s the weather like in Sydney?

____

② Can I go outside now?

____

③ It’s hot and sunny in Beijing.

____

④ Is the weather cold in Harbin?

____