1666年3月5日上午6.30用英语怎么说

at 6:30 on the morning of March 5,1666.

6:30 in the morning on fifth of March in 1666.

口头说是
on the morning of half past six of March 5th 1666.

书面上写的话就是
March 5, 1666 6:31 AM

1666年3月5日上午6：30
Half past six,March5,1666
读为：At half past six AM. in March the fifth of 1666.
上午书面一般表示为:AM.