搜题请搜索小程序“爱下问搜题”
问题 选择题

近年来北方地区沙尘暴频繁发生，其主要原因是（　　）

A．自然灾害

B．北方寒流入侵

C．频繁的地壳运动

D．过度放牧破坏生态环境

答案

沙尘暴发生不仅是特定自然环境条件下的产物，而且与人类活动有对应关系．人为过度放牧、滥伐森林植被，工矿交通建设尤其是人为过度垦荒破坏地面植被，扰动地面结构，形成大面积沙漠化土地，直接加速了沙尘暴的形成和发育；因此扩大畜牧业发展会对草原植被造成破坏，增加了土地沙漠化的进程，不利用防治沙尘暴的发生．

故选：D

阅读理解
阅读理解。
     Summer holidays are coming soon. Are you going to travel? If you plan to take a plane, you will have a
healthy trip by following these suggestions (建议).

1. Bring some needed medicines in your carry-on bag.
2. Don't leave your seat during the plane's take offs and landings.
3. To prevent blood clots (血流不畅):
★ 1______
★ Do leg-stretching (伸) exercises in your seat.
★ Wear comfortable clothes.
4. If you sometimes get airsick:
★ 2______ 
★ Keep your seat belt fastened (系好安全带).
★ Don't take small planes.
5. 3______  Don't take wine or alcohol (酒).
6. Use both hands when reaching overhead for something. 4______ 
A. This will help prevent yourself from getting hurt.
B. Better drink water or juice when you feel thirsty.
C. Get up and walk around every 60 to 90 minutes.
D. Ask for a window seat or a seat over the wing.
5. What's the best title for the passage?
A. A Plan for Summer Holidays.
B. Suggestions for an Interesting Trip.
C. Suggestions for a Healthy Air Trip.
D. Problems during an Air Trip.
查看答案
单项选择题 A1/A2型题

以下不属于肉瘤组织学特点的是（）。

A.实质与间质的分界不清

B.瘤细胞间有网状纤维穿插、包绕

C.瘤细胞形成巢，巢周围有网状纤维包绕

D.间质少、血管丰富

E.瘤细胞弥散分布
查看答案