8点半，九点，12点半，2点半，4点半，7点用英语说

不会吧，这问题也……
有两种表达方式

八点半，half past eight（half 是一半的意思，past是过，意思就是八点过半）
九点，nine o'clock
12点半，half past twelve
2点半，half past two
4点半，four thirty(传统表示方法，直接说数字)
7点 seven o'clock

8点半: half past eight
九点:nine o'clock
12点半:half past twelve
2点半:two o'clock
4点半:four o'clock
7点:seven o'clock

8.30 half past eight
9. 9 o'clock(9.00a.m.)
12.30 half past twelve
2.30 half past two
4.30 half past four
7 7 o'clock

这样的问题也来问，幼儿园出来的吧！

half past 8
9 o'clock
half past 12
half past 2
half past 4
7 o'clock

half past eight
nine o'clock
half past twelve
half past two
half past four
seven o'clock