2023年事理说明文300字初二8篇(模板)

事理说明文300字初二篇一

森林资源是人类赖以生存的基础资源。同时，森林还具有维护地球生命、改善人类生存环境的生态价值。

森林可以给人类源源不断地提供木材产品和林副产品。木材产品主要包括原木、锯材、纸浆材、人造板材等;林副产品主要包括森林动物与微生物提供的各种产品等。为人类提供这些产品无疑是森林的重要功能。

森林是生态平衡的主要调节器。森林可以把太阳能转化为化学能，使无机物转变为有机物，是生物和非生物之间物质和能量交换的重要纽带，对保持生态系统的整体功能起着中枢和杠杆作用。可以说没有森林就没有生态平衡。

森林能够有效地涵养水源和防止水土流失。森林凭借庞大的林冠、深厚的枯枝落叶层和发达的根系，能够起到良好的蓄水保土和减轻地表侵蚀作用。据测算，5万亩森林的蓄水量约有一百万立方米。在森林被破坏或无森林的地区，水土流失严重，许多河道和水利设施不断受到泥沙淤积，经常造成水灾。

森林能够有效地保护生物多样性。目前地球上的500～3000万种生物中，有一半以上是在森林中栖息繁衍。

森林能够有效地缓解“温室效应”。由于近代人类大量使用石化燃料，使大气中二氧化碳、甲烷等温室气体浓度不断升高，引起地球上的“温室效应”。每公顷森林平均每年可吸收20～40吨二氧化碳，同是放出15～30吨氧气。据有关专家研究，一公顷森林平均每年能吸引700多千克的二氧化碳，可减轻工业酸雨的危害;城市中路旁的林带可以阻挡沙尘，滞尘率高达70%～90%。同时林带还有降低噪声的作用，噪声经过30米宽的林带可降低6～8分贝。

森林能产生直接的经济效益，同时又有巨大的生态环境效应，这是任何其他东西都无法替代的。

事理说明文300字初二篇二

in english class, we had a heated discussion on the quality of computers. the advantage is that computers can solve math problems quickly. you can also store information such as stories and documents in it.

we also think of the disadvantages. that is, if you use computers for a long time, it is not good for your health. i think the conclusion is that computers are good, but we should not use them for a long time computers are very useful to us.

the internet is a great facility for collecting information. the internet makes it easy for us to establish social connections. we can have many friends all over the world and acquire a lot of knowledge through the internet.

today, millions of people exchange e-mail through the internet. however, the disadvantages of computers are that many network information may be false, and network socialization will weaken us the ability to deal with relationships in the real world. the weak may be addicted to online games and online entertainment, thus destroying their own career.

the loveliness of the internet is infinite and colorful, but we can only make good use of it to strengthen the management. although we have an appropriate way to surf the internet, you think computers play a very important role in our daily life. thousands of people surf the internet every day.

with the help of the internet, you can get a lot of useful information. you can make friends with different people, no matter they whether you know it or not, you can ask for help or ask for answers. every coin has two sides.

there is so much garbage on the internet. these garbage are some media information about crime or sex. the cost is higher.

it also makes people waste time on it. its ability should be used by people. we should make good use of the internet to make our life better.

中文翻译：

事理说明文300字初二篇三

森林是以树木为主体的许许多多生物组成的生物群落。森林里蕴藏着丰富的资源，森林资源按自然属性可划分为生物资源和非生物资源两大类。其中生物资源又可分为植物资源、动物资源和微生物资源三类。植物资源包括林木资源（乔木、灌木和竹子）和非林木资源（藻类、地衣、苔藓、蕨类和其他种子植物等）；动物资源主要包括哺乳动物、爬行动物、森林昆虫、鸟类和鱼类等；微生物资源主要包括各种菌类、支原体、衣原体等。非生物资源主要是指支撑森林生物的林地土壤、水分等资源。可见森林是地球上一个丰富多彩的大资源库，而且其主要部分即森