(Part Two) GRADE: A "grade" is what I get after a course of study. Grades are ranked so that someone who obtained an A grade is deemed to have grasped the concepts of the course more thoroughly and can demonstrate or apply their acquired knowledge or skills with greater ease as compared to someone with a C grade. Grades can also be applied to differentiate the quality of other things such as commodities. They provide a basis for comparison of value. Of course, "grade" can be used as a verb. For example, these handicrafts are graded according to their level of detail and intricacy. BIODEGRADE: "Bio" is a prefix to refer to life. "Biodegradable" materials can degrade or decompose naturally with the help of microorganisms such as bacteria or other living organisms. For example, some plastics are now biodegradable so that they will not linger around forever and cause excessive litter. When biodegradable materials such as kitchen food scraps are left to "decompose", they will form "compost" (I am not sure if you meant "compost" in your question). "Compost" is a mixture of decayed organic material that is very rich in nutrients and can be used as a fertiliser for plants. Do not confuse "decompose" with "compost". When living things die, they will naturally "decompose" due to bacterial and fungal activity. That's it! I hope this helps.

(Part One) Hi Hasan, Degrade: "Degrade" means the breakdown of a substance chemically to form simpler structures. For example, when we consume meat, our digestive system uses enzymes to break the chemical bonds of the protein molecules. The result of this "degradation" process is a mix of smaller amino acids. Degrade also has the meaning that the value, quality or usability of something is lowered. For example, DNA that has been exposed to ultraviolet radiation and other weather elements will degrade over time and be rendered useless to forensic scientists. We can also degrade someone by belittling others and treating others in a condescending matter, making other feel inferior and lousy about themselves. For example, a bully can tease someone and degrade the victim. If I act in a way that causes others to lose respect for me, I am "degrading" myself. DOWNGRADE / UPGRADE: When we are willing to settle for something less than what we are used to, we "downgrade". For example, I can sell my four-room flat and move into a two-room flat. I have just downgraded my accommodation. We can also use this word in finance. For example, countries have credit ratings and various agencies will assign a rating to each country. When that rating goes down (e.g. from Aa2 to Aa1), it has been downgraded. On the other hand, we "upgrade" to get something of a higher quality or receive better service. For instance, the hotel which I patronise regularly has decided to "upgrade" my stay from a standard suite to a presidential suite at no extra charge. I can also pay more to upgrade my air fare from economy to business.

Hello, These are great questions and I am happy to help! The definitions below are from Merriam-Webster Learner's Dictionary. If you are interested, it is a great resource for English language learners. It's available here: http://learnersdictionary.com/ 1. degrade: to cause (something complex) to break down into simple substances or parts 2. downgrade: an occurrence in which something becomes worse, less valuable, etc. 3. grade: a particular level of quality 4. upgrade: a [+ object]: to make (something) better by including the most recent information or improvements 5. biodegrade: (of a substance or object) be decomposed by bacteria or other living organisms 6. decompose: to cause something (such as dead plants and the bodies of dead animals) to be slowly destroyed and broken down by natural processes, chemicals, etc. You asked the meaning of 'compose', but I think that you meant decompose. If something is biodegradable, it is able to decompose. Grade, downgrade and upgrade usually refer to the quality of an object or thing. Degrade is most commonly used to describe how a person is treated unless you are using the technical definition of the word. I hope this answer helps you. If you have further questions about English, I am available for professional English lessons. You can find my profile here: https://www.italki.com/teacher/5129645 Have a great day and happy learning!

Wow. That's some advanced English you are studying! Degrade, most common way of using this is as "degrading," as in disrespectful. The man made a really degrading joke about women. Much less common is to use degrade as in come apart or break down. "Plastic is terrible for the environment because it takes so long to degrade." Downgrade, most common use is to go down in quality. I am downgrading my subcription from Elite to Basic. Or the man downgraded from using premium gasoline to regular. Grade, most common use is a sign of performance (or a "mark" in Britain) . What grade did you get on the test? Can also be used for quality. What grade of gas do you want? Premium or regular? Upgrade, opposite of downgrade Biodegrade is has the same basic meaning as to compost but no one would use it that way. "I need to compost my leftover vegetables" . You wouldn't say I need to biodegrade my vegetables. Most common way to use this is as biodegradable. So scientists might talk about something that is biodegradable, which means that it it's basically a substance that will break down organically (or DEGRADE organically!)