在大气污染中对植物危害较大的是()
A、一氧化碳和二氧化硫
B、二氧化硫和氟化物
C、一氧化碳和氟化物
参考答案:B
Many houses were destroyed in the heavy rain. They should get them _____. [ ]
A. to repair
B. repaired
C. repairing
D. repair
树木按其观赏性分类,一般分成哪几类?各类的主要特点是什么?