diff --git a/day2/README.md b/day2/README.md
index 680389c..a702541 100644
--- a/day2/README.md
+++ b/day2/README.md
@@ -1,4 +1,4 @@
 ## 简并
 ### 'a/=2'   ==   'a=a/2'
 ## 切片
-### x[ a: b :c ]中c代表距 默认是1
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+### x[ a: b :c ]中c代表距 默认是1(所以-1是倒过来)
\ No newline at end of file