分类：教育/科学-学习帮助
问题：帮帮忙？急　　　theresultsareevenmoreser 
the results are even more serus, for where there are their roots_______ the soil up allowing the rain to sink in and also the soil, thus preventing it being washed away easily帮忙看看该选什么,为什么? 怎么翻译? 
回答：tighten.

这样的后果很严重，因为它们的根系固紧土壤并使得雨水容易渗透进土壤，同时土壤也（通过它们的根系）保护它们免被冲走。