以下哪种疾病累及脊髓前角细胞
A．肌萎缩性侧索硬化
B．进行性脊肌萎缩
C．脊髓空洞症
D．脊髓灰质炎
E．脊髓亚急性联合变性
参考答案：A,B,C,D
在“研究透镜成像规律”的实验中，请你设计一个测量透镜焦距的简易方案，
写出实验步骤：
（1）______；
（2）______．
评估你的实验方案的优缺点：______．
Unfortunately, it was in Yushu County, ______ a 7.1-magnitude earthquake happened on April 14, 2010, ______ a large number of students were buried inside damaged schools.
A．which; when
B．that; that
C．where; that
D．where; which
