问题 单项选择题

氢氧化钙盖髓剂作用如下,除外()

A.中和炎症产物的酸性

B.抗菌作用

C.强碱性

D.安抚作用

E.促进硬组织形成

答案

参考答案:D

阅读理解

阅读理解。

                    Find Which Direction Is South

     Do you have a good sense of direction? If not, please take

with you a compass. But if you forget to take a compass, you

can still find your way.

     It's never a good idea to imagine that the family member

who was entrusted (委托) with the job of map-reading actually

knows where the family is. You can tell by the slightly

confused load on their faces that nothing on the ground seems

to match the map. Never mind. The sun is shining and it's still

morning.If you don't know the exact time, you can still find

out where south is, but you'll need to be patient.

    ①Find a straight stick and put it in the ground in a place

where you can mark its shadow.

    ②Try to position the stick as vertically(垂直)as you can.

You can check this by making a simple plumb line (铅锤线)

with a piece of string and weight. You haven't got any string?

OK, use a thread from your clothes with a button tied at the

end to act as a weight.

    ③Mark the end of the shadow cast by the stick.

    ④Wait approximately half an hour and mark the end of

the shadow again.

    ⑤Keep doing this until you have made several marks.

    ⑥The mark nearest the stick will represent the shortest

shadow, which is cast at midday, when the sun is highest in

the sky and pointing to the exact south.

    ⑦Pick a point in the distance along the line between the

shortest shadow and the stick.

    ⑧That point is south of where you are.

    ⑨Now you can turn the map, like you did before, and

find which way you should be travelling.

1. To find the direction, we ought to be patient probablybecause ____ .     

A. it is not easy to find a proper stick

B. it is not easy to position the stick

C. it takes hours to make the marks

D. it takes about half an hour to make the marks

2. The passage would probably be most helpful to ____. 

A. those who draw maps

B. those who get lost

C. those who make compasses

D. those who do experiments

3. Which of the following pictures best shows the way of finding the direction of south?

4. The author presents this passage by _____.

A. telling an interesting story

B. describing an activity in a lively way

C. testing an idea by reasoning

D. introducing a practical method

单项选择题 A1/A2型题