Question

it's the third time __late this month

Answer 1

It is the third time that he has been late this month.
这个句型结构是：是某人第几次做某事
It is the frist time that I have seen an elephant. 这是我第一次看到大象。
注意：It was the first time that I had seen an elephant.(特别要注意时态)
还有一个句式和它是相同的：(把第几次换成了最高级)
It is the most interesting film that I have ever seen.这是我看过的最有趣的电影。
It was the most interesting film that I had ever seen.(特别要注意时态)

Answer 2

of

Answer 3

it's the third time I've been late this month.
这是我这个月来第三次迟到了。