下列有关生物生殖发育的说法中不正确的是
A．桃树进行有性生殖时重要的环节是传粉和受精
B．嫁接时应当使接穗与砧木的维管束紧密结合以保证营养物质的输送
C．通过组织培养保持名贵花卉的优良性状
D．鸟类的生殖和发育过程一般包括求偶、交配、筑巢、产卵、孵卵和育雏等几个阶段
答案：B
题目分析：嫁接是指把一个植物体的芽或枝，接在另一个植物体上，使结合在一起的两部分长成一个完整的植物体，嫁接时，接上去的芽或枝叫接穗，被接的植物叫砧木，嫁接时应当使接穗和砧木的形成层紧密结合，以确保成活，因为形成层具有很强的分裂能力，能不断分裂产生新细胞，使得接穗和砧木长在一起，易于成活，选B。
Do you often feel weak or tired when you get up in the morning? Do you often wake up with a headache? Well, if the answer is yes, take Dr. Talbot’s advice (建议) and start feeling better. Get up and move. If you hate feeling tired and unhappy, you should start exercising. Try running, swimming or cycling. When we exercise, our body produces special chemicals(化学产品) that give us energy and make us feel happier. If you dislike exercising, listen to your favourite music and dance to it. That’s exercise, too. Eat healthily. You should eat three balanced meals every day and you shouldn’t eat too much fast food. If you need some more extra energy the whole day, make an energy drink. Mix together fresh fruit juice and low-fat milk. It tastes great. Get out close to the open air. The smell of flowers will make you feel happy. Even the smell of your favourite food can change the way you feel! Wake your body up. When you have a shower, change the water from hot to cold and back to hot again. You’ll feel the difference. Laugh! You should laugh for, at least, three minutes, three times a day. It will make you feel great!
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