阅读下面的短文，将划线部分的句子泽成汉语或英语。
Reading is a very important skill. 阅读也是一种提高你的英语的好方法。However, to make sure what you read isn't too difficult, it's important to know what makes texts difficult and how you can improve your understanding of them. Here are some suggestions.
①Understand the purpose of your reading. The way you read depends on the purpose of your reading. The kind of reading you do in class or for your homework is different from how you read a novel for pleasure in the summer holidays.
② Find background information. Find something out about the topic you are going to read.
The more background information you have, the easier it'll be to understand the text.
③Increase your vocabulary（词汇）. The more vocabulary you have, the easier your reading will be.
④ Use your dictionary correctly. A common mistake is to read everything very slowly and carefully, looking up each unknown word. Sometimes this is necessary, for example, when reading exam questions. However, it takes a long time and can be very boring; it can even make understanding more difficult!
If you've followed the above advice and still can't understand a text, then it's simply too hard for you. Stop reading and ask someone to help you. 没有人想要放弃。However, you'll just be wasting your time if you continue to work at a text that's beyond you.
4CO2+2R+6H2O，则R的化学式是（ ）