如图所示甲、乙、丙三细胞相邻，箭头表示细胞间水流的方向，则表明（ ）
A．甲细胞的细胞液浓度最小
B．乙细胞的细胞液浓度最大
C．丙细胞的细胞液浓度最小
D．乙和丙细胞的细胞液浓度相等
根据图中箭头表示细胞间水流的方向，水分总是由浓度低的地方向浓度高的地方流动，在根毛区中，土壤溶液的浓度小于根毛细胞液的浓度，根毛细胞液的浓度依次小于内部细胞的细胞液的浓度，水分就会从土壤依次经过根毛细胞、成熟区细胞到达内部的导管了．从图示中可以看出：水流的方向甲流向乙和丙，乙也流向丙．丙细胞的细胞液浓度最大，甲细胞的浓度细胞液最小．
故选：A．
Have you had a headache during a test Have you ever been so worried about something that you have a headache or even can’t sleep at night If so, then you know what stress is. Stress is what you feel when you are worried about something. This worry in your mind can make your body feel bad. You may feel angry, sad, scared, or afraid—all of which can give you a stomachache or a headache.
However, there are different kinds of stress. Some kinds of stress are good and others are bad. Good stress might happen when you’re called to answer questions in class or when you have to give a speech. This kind of stress can help you to get things better done. For example, you may do a better job on your test if the stress pushes you to prepare better before the test.
On the other hand, bad stress can happen if stress lasts too long. You may not feel well if your parents are fighting, if a family member is sick, if you’re having problems at school, or if anything else makes you unhappy every day. That kind of stress isn’t going to help you. And it can actually make you sick.
The best way to fight stress is to have a balanced life. Make sure you keep your SELF in mind: Sleep, Exercise, Leisure(休闲), and Food. If you get enough sleep and eat properly, and if you exercise and leave time for fun, you’ll probably feel less stressed.
| Title: Face the Stress | ||
| Meaning of stress | Stress is a (68) when you are worried about something. | |
| Possible effect | You may feel uncomfortable in your (69) and body. | |
| Good stress | · It might happen when you have to (70) in public. · It will be more (71) for you to do the job successfully. · It makes you (72) better before doing the job. | |
| Different kinds | Bad stress | · It might happen if your stress (73) too long. · You may not feel well with the (74) of a family member, problems at school or something else that worries you every day. · It might stop you from getting your work well done. |
| How to keep stress (75) | Have a balanced life. · Have enough sleep and have (76) food. · Take exercise and have time to (77) yourself. | |