设计一个实验方案，以验证“二氧化碳是光合作用合成有机物必需的原料”，基本步骤如图所示，请回答问题

北美洲的落基山脉的成因可以这样解释（    ）

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.