—Tom, you never told me why you were late for school again,_____ you?        
—____. But maybe you forgot it, sir.                           

在生活中，我们要从点滴小事做起，注意节约用水，节约用电，你认为切实可行的措施是（ ）

Today（今天） is Sunday. The weather is warm and windy. I can wear my shirt（衬衣） and jeans牛仔裤). I fly a kite on the playground. Tom and Jack wear their T-shirt and shorts. They play football. But in Harbin, it's cold. It's snowy. People put on their coat and hats. They can make a snowman(雪人) and skate(滑雪). It’s funny.

It's windy. So I can fly a kite.

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(               )