Write a passage of at least 50 words on the topic “ Trees are important”. ( 以“树是重要的”为题写一篇不少于50个词的短文，标点符号不占格。)

Use the following points as a reference.（以下问题仅供参考）

Why trees are important?(Give at least three reasons)

What would happen without trees?

How can we protect trees?

公有制经济在我国国民经济中占主体地位，主要体现在[ ]

①公有资产在社会总资产中占优势

②国有经济控制着国民经济命脉

③数量最多，分布最广

④实现了人民的共同富裕

A．①③

B．①②

C．③④

D．①④