拒绝邀请

I'm not sure about it. I'll have to check.
我不大清楚。我看一下吧。
A: Are you free next Saturday?
下周六你有空吗？
B: I'm not sure about it. I'll have to check.
我不大清楚。我看一下吧。

I will be busy all day long．
我一整天都会很忙。
A: Are you free today?l have something to tell you.
今天你有空吗？我有事要告诉你。
B: Sorry, I will be busy all day long.
对不起，我一整天都会很忙。
all day long“整天”

I won't be free until Wednesday.
周三前我都没空。
A: I won't be free until Wednesday.
周三前我都没空。
B: Then what about Thursday?
那周四怎么样？

Any time except this Sunday.
只要不是这个星期天，什么时间都可以。
A：Sorry, any time except this Sunday.
对不起，只要不是这个星期天，什么时间都可以。
B: Then how about this Saturday?
那这个星期六可以吗？
except和but都可以作介词来表示“除了…”。

I have to work overtime tonight．=I have to work extra hours tonight.
我今晚要加班。
A: Sorry,I have to work overtime tonight
对不起，我今晚要加班。
B:Then have a cup of coffee with me after work.
那你下班后我们一起喝杯咖啡吧。
overtimer n. 加班 extra a. 额外的

I'll have to attend a conference that day.
那天我得出席一个会议。
A：Would you like to attend our wedding next Saturday?
下周六你能参加我们的婚礼吗？
B: Unfortunately, I'll have to attend a conference that day.
不凑巧，那天我得出席一个会议。
unfortunately ad. 不幸地
have to意思是“不得不，必须”，含有不情愿的意思。

I'd love to, but l couldn't.=I'd love to, but I can't.
我很乐意，但是我不能。
A: Let's have some drinks.
咱们去喝酒吧。
B: I'd love to, but I couldn't.
我很乐意，但是我不能。

I don't feel well.
我不太舒服。
A: Thank you for inviting me, but I don't feel well.
谢谢你的邀请，但是我不太舒服。
B: Then have a good rest. Maybe next time.
那你好好休息。或许下次吧。