I'm afraid I have to go,( )I'll miss the birthday party.A.but B.or C.then D.and

I'm afraid I have to go,( )I'll miss the birthday party.A.but B.or C.then D.and
I'm afraid I have to go,( )I'll miss the birthday party.
A.but B.or C.then D.and

I'm afraid I have to go,( )I'll miss the birthday party.A.but B.or C.then D.and
B.or 否则 意思是 ：我不得不要走了 否则我将会错过这个生日宴会