题目

观察DNA和RNA在细胞中的分布，所运用的原理是( ) A．单独利用甲基绿对细胞染色可显示DNA在细胞中分布，从而推知RNA的分布 B．单独利用吡罗红对细胞染色，可显示RNA在细胞中的分布，从而推知DNA的分布 C．利用甲基绿和吡罗红混合染色剂对细胞染色，同时显示DNA和RNA在细胞中的分布 D．在细胞核、细胞质内可以分别提取到DNA和RNA，由此说明DNA和RNA的分布  31、Never try to work when you are hungry. If you decide to do your homework right after school, you may get something to eat before getting to work.       Always do your homework before you get too tired. Don't wait until very late in the evening, or your homework will seem much harder than it really is.      If you have more than an hour's work, give yourself a break after an hour. On the other hand, don't break it up so much that you can't get anything done. You should be able to work at least a half hour at a time without stopping.       Don't put it off until the last minute. If you put off doing your homework, you will have it on your mind, and you won't enjoy your free time so much. If you put it off until the end of the week or until right before a test, you will have too much catching up to do. A little bit each night, enough to keep up with what is happening each day in school, will take the fear out of tests and keep you on top of it.      Do your homework at the same time every evening. This will help you make it a habit. It will make it easier to do, and it will make your free time more enjoyable, as well. 1. If we wait very late in the evening, our homework will _________.      A. become a bit hard      B. seem much harder      C. look very easy      D. get us into so much trouble 2. Some students in schools won't enjoy their free time so much because they______.      A. have to do their homework each night B. will have too much catching up to do C. never finish their homework in time D. want to keep up with what is happening in school 3. What does the underlined word "habit" mean in Chinese?     A. 制度    B. 风格     C. 传统     D. 习惯 4. How many main ideas are mentioned in the passage?      A. Five       B. Three      C. Four.       D. Two 5. Which could be the best title for this passage?      A. Do Your Homework at the Same Time    B. A Must for Doing Your Homework      C. Don't Try to Work When Hungry         D. Some Don'ts and Dos in Schools