it is 600 years since the first clock with a face and an hou

it is 600 years since the first clock with a face and an hou It was aout 600 years ago ()the first clock with a face and It was about 600 years ____ the first clock with a face and It was about 600 years ago____the first clock with a face an It was about 600 years ago that the first clock with a face It was about 600 years ago______the first clock with a face It was about 600 years ago_______the first clock with a face the first clock with a face and an hour hand was made about it is three years since they __ with each other,and they are 英语翻译it's a museum .it's towhundred years old .and clock is f it is four years since i an english teacher 1.It is two years ＿I joined the army.A.before B.since C.that