Что означает : a quarter to six

В чем разница во времени в английском между "quarter" и "a quarter" если можно писать и так и так? напр: It's quarter past three It's a quarter to four

Выберете правильный вариант предложения 1) they have known each other for six years 2) she will knew each other for six years 3) they has known each other for six years 4) he shall know each other for six years 5) they are knowing each other for six

1. It's twenty to one 2 It's twenty past twelve 3. It's five to one 4. It's a quarter to twelve 5. It's half past twelve 6. It's a quarter to twelve 7. It's a quarter past twelve 8. It's noon 9. It's five past twelve 10.

What time is it? (Ex. It's quarter past ten - 10.15) It's quarter past five. It's half past eight. It's quarter to twelve.

What time is It? (ex. lt's quarter past ten - 10.15) It's quarter past nine. It's half past two. It's quarter to four.