1. In my opinion/view 通常用来讨论较重要的事情
In my view, our performances at the moment have been affected by tiredness.
2. It seems to me/All things considered 常用来表达经过深思熟虑后的意见
It seems to me that this crime was foreseeable and that this death was preventable.
All things considered, I think we made a wise choice in recruiting James.
3. I suspect that...表示疑心（较肯定、正向语气）
It implies to the listener that they could disagree and you wouldn't be offended.
I suspect that he was lying.
4. I wonder if... 表述一个你认为可能正确的想法
It says you're contemplating if your statement is correct, and encouraging the listener to tell you their opinion.
I wonder if you'd be kind enough to call him.
5. To be honest/To tell you the truth/To be frank 如果需要说些不讨喜的话
To tell you the truth, your plan is unrealistic.
To be honest, the house is not quite our style.
To be frank, I don't like him.