Отрезки АВ i CD пересекаются в точке О и делятся этой точкой пополам. Докажите, что AC ‖ BD

Don't you
Can't you
Isn't it
Won't you
Do they
Have they
Don't they

1.You know evrything about English grammar, don't you?
2.You can tell an American from an Englishman when you talk to them, can't you?
3.English is taught in all schools of Russia, isn't it?
4.You will start learning Chinese this year, won't you?
5.Students don,t like to do test in English or other goreign languages, do they?
6.Your parents have never learnt English , have they?
7.Nowadays all educated people school speak English during the break-times as well as during the English lessons, don't they?