问题 问答题 简答题

详述植物病害的侵染循环。

答案

参考答案:

植物病害的侵染循环是指从前一个生长季节开始发病,到下一个生长季节再度发病的过程。侵染循环一般包括三个环节:初侵染和再侵染;病原物的越冬;病原物的传播。传播途径有气流、雨水、动物、人为等。

单项选择题

The comprehension passages on this course are designed to help you increase your speed. A higher reading rate, with no loss of comprehension, will help you in other subjects as well as English, and the general principles apply to any language. Naturally, you will read every book at the same speed. You would expect to read a newspaper, for example, much more rapidly than a physics or economics textbook but you can raise your average reading speed over the whole range of materials you wish to cover so that the percentage gain will be the same whatever kind of reading you are concerned with.

The reading passages which follow are all of an average level of difficulty for your stage of instruction.

If you get to the point where you can read books of average difficulty at between 40 and 50 w.p.m. with 70% or more comprehension, you will be doing quite well, though of course any further improvement of speed with comprehension will be a good thing.

When you practice reading with passages shorter than book length, do not try to take in each word separately, one after the other. It is much more difficult to grasp the broad theme of the passage this way, and you will also get stuck on individual words which may not be absolutely essential to a general understanding of the passage. It is a good idea to skim through the passage very quickly first (say 500 words in a minute or so) to get the general idea of each paragraph. Titles, paragraph headings and emphasized words (underlined or in italics) can be a great help in getting this skeleton outline of the passage.

Provided there is no loss understanding, a higher reading speed will help in ().

A. English

B. physics

C. other subjects as well as English

D. economics

单项选择题