脊柱结核与脊柱肿瘤X线片的鉴别要点是（）
A.椎间隙变窄
B.椎体破坏
C.椎体高度变低
D.椎体后壁破坏
参考答案：A
经过两年的连续治理，某城市的大气环境有了明显改善，其每月每平方公里的降尘量从50吨下降到40.5吨，则平均每年下降的百分率是______%．
Directions:
Write an essay of 160 -- 200 words based on the following cartoon. In your essay, you should
1) describe the cartoon briefly,
2) explain its intended meaning, and then
3) support your view with an example/examples
You should write neatly on ANSWER SHEET 2.
