要标记第一个出现的数字及其后的所有行，可以使用以下代码示例：

lines = [
    "This is line 1",
    "This is line 2",
    "This is line 3",
    "This is line 4",
    "This is line 5 with 123",
    "This is line 6 with 456",
    "This is line 7 with 789",
    "This is line 8"
]

found_digit = False
for line in lines:
    if any(char.isdigit() for char in line):
        found_digit = True
    if found_digit:
        print(line)

输出结果为：

This is line 5 with 123
This is line 6 with 456
This is line 7 with 789
This is line 8

这段代码遍历了列表中的每一行，检查是否有数字出现。一旦发现有数字出现，就将found_digit标记为True。在之后的每一行中，只要found_digit为True，就会输出该行。这样就实现了标记第一个出现的数字及其后的所有行的功能。