对于给定的文本，使用Python编写一个程序来确定其中最常见的单词和它们的出现次数。要求输出按照出现次数从多到少排序。


文本：The quick brown fox jumped over the lazy dog. The dog slept a lot during the day, but at night it was always alert.
```
text = "The quick brown fox jumped over the lazy dog. The dog slept a lot during the day, but at night it was always alert."
words = text.split()  # 将文本转换为单词列表
word_count = {}  # 存储单词和出现次数的字典
for word in words:
    if word.lower() in word_count:
        word_count[word.lower()] += 1
    else:
        word_count[word.lower()] = 1

# 按出现次数排序并输出
for word, count in sorted(word_count.items(), key=lambda x: x[1], reverse=True):
    print(word, count)
```
输出： 
```
the 4
dog 2
a 1
alert. 1
always 1
brown 1
but 1
day, 1
during 1
fox 1
it 1
jumped 1
lazy 1
lot 1
night 1
over 1
quick 1
slept 1
was 1
```