用并列连词连接两个句子!he was tired .he went to bedhe made a promise.he didn't keep itmary is opening the door.john is greeting her guests

he was tired so he went to bed
he made a promise but he didn't keep it
mary is opening the door while john is greeting her guests

Because he was tired ,so he went to bed。
He made a promise,but he didn't keep it.
After Mary is opening the door,john is greeting her guests .

He was tired thus/so/therefore/hence he went to bed.
He made a promise however/but/neverthless he didn't keep it.
Mary is openning the door while John is greeting her guests.

so
but
and

1.he was tired,so he went to bed.
2.he made a promise but he didn't keep it.
3 mary is opening the door,and john is greeting her guests