题目

小白兔生物体内不同的组织细胞中所含的DNA和RNA是(   ) A.DNA相同，RNA也相同    B.DNA相同，RNA不相同 C.DNA不相同，RNA相同    D.DNA不相同，RNA也不相同 答案：B 解析: 不同的组织细胞由同一受精卵经过有丝分裂形成，细胞核中DNA相同，在形成不同的组织细胞的细胞分化过程中，基因选择性表达，因而转录的RNA不同。根据短文内容，从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。How to pass an important testWhether it's a first grade science test or College Entrance Exam, all tests have one thing in common: you have to pass. __【1】_ Stuck in a situation where you don't know what to do? This article can help.Tips★1. Once you get the study guide, make plans right away to study as soon as possible. No excuses! Killing time with friends isn't worth it，since you can always hang out with them any other day.★2. Get plenty of rest. _【2】If you walk into the classroom sleepily, you'll most likely not finish the test because you are so tired.★3. Eat a good meal for breakfast. __【3】__ Some healthy breakfast suggestions are oatmeal (燕麦片), high fibre food, and grapefruit with the fresh fruit salad.★4. Bring all necessary materials. ___【4】__ Bring pencils, pens, pencil sharpeners, snacks (if allowed)，erasers, the calculator (if allowed) and anything else you'll need for the test.★5. __【5】___ Showing up late cuts back the time you'll have to take for the test if it's already testing hours. You'll probably miss any important information needed in completing the test. In some tests，late comers are not allowed to take the test.A．The exam tests vocabulary, reading and maths skills.B．Studies show that if you get enough sleep, your brain will be much more efficient.C．Failing the test won't help you in the long run, so it's important to know how to prepare to pass that big test.D．Showing up without something as simple as a pencil can make a big effect on your test.E．One piece of cheese probably won't last until test time.G．Don't forget to set your alarm clock and show up on the test day on time.F．This test is a challenging one and every year many students are unable to qualify it just because of lack of guidance.