在进行性肌营养不良症患者发病中起主导作用的因素为_________即病理基因所引起的一系列酶及生化改变。
参考答案：遗传因素
氯化钠样品中混有少量碳酸钠，某学生欲用下面两种方法进行提纯．
方法一：样品溶于蒸馏水，加稍过量盐酸，蒸干溶液．
方法二：样品溶于蒸馏水，加稍过量石灰水，过滤，向滤液中加稍过量盐酸，蒸干溶液．
你认为这两种方法中______不合适，理由是______．
用 when或 while填空。
1. I was looking out of the window _________ the teacher asked me.
2. What is he doing _________ his parents came back？
3. Mike was playing games _________ Jack was studying.
4. I was about to fall asleep _________ the baby began to cry.
