问题 问答题 简答题

园艺作物品种混杂退化的原因是什么?如何防止其退化?

答案

参考答案:

(1).混杂退化的原因①机械混杂②生物学混杂③不重视选择,缺乏选择制度而造成的退化④留种株数过少而造成的退化⑤自然条件、栽培条件不适当而造成的退化。(2).防止退化的原因①防止机械混杂②防止生物学混③重视选择,健全选择制度④留种株数超过100株防治退化⑤创造最适合的自然条件、栽培条件防治退化。

阅读理解

Depressed people can be very difficult to be around,and yet they need more than the usual amount of support and understanding from their friends and family.

The anger and lack of concern that a depressed person may have for people close to him or her can be very disturbing to someone who's trying to help.At such times,the sincerity of a friend or a family member is questioned when the depressed person doesn't feel worthy of someone's friendship.Withdrawal from others can make it nearly impossible to encourage a depressed person to enter into activities that may help pull him or her out of the depression.

It is frequently difficult for a depressed person to carry on a conversation.Attempts to help may be met with defensiveness and verbal attacks.While being supportive and understanding,the friend of a family member must be careful not to do too many things for the depressed person.There is a very thin line between being supportive and being overly protective.Too much“doing for” can be a disservice(帮倒忙).

You can best help a friend or relative who is depressed by considering the following points:

◆Do not moralize.Don't pressure him or her to “put on a happy face,” or to “snap out of it.” Often the person will feel even worse after hearing such words.

◆When you are alone with your depressed friend,you might say something like,“I've noticed lately that you seem down.I care about you and would like to listen to what you're thinking about.” Then be a good listener.

◆Don't say,“I know exactly how you feel.” You probably don't.But if you've had similar experiences,sharing those may help.Say things like,“This happened to me.It might help you.” Or “I know some of what you must be feeling.”

◆Urge him or her to get professional help if necessary.Offer to accompany your friend on the first visit if it will be easier for the person.

小题1:.The above passage is mainly intended for ________.

A.a doctor who works with a depressed person

B.a depressed person

C.one who lives with a depressed person

D.an expert who gives advice to a depressed person小题2:Too much “doing for” can ________.

A.cause more severe depression

B.give the depressed person courage

C.result in defensiveness from the depressed person

D.be of no help to the depressed person小题3:What are you advised to say to a depressed person?

A.Try to look happy and you'll be better.

B.I know exactly how you feel.

C.I had a similar experience.And it might help you.

D.Cheer up and get rid of your depression.小题4:We can infer from the second paragraph that a depressed person ________.

A.is willing to appreciate the sincerity of a friend or a family member

B.has a sense of pride of his own

C.may do something unreasonable to your friendship

D.is likely to doubt the purpose of a friend or family member

单项选择题