I'm sure they'll be really successful.
我肯定它们将非常成功。
A I'm very impressed with all the preparations for the Olympics.
A 对奥运会的召开所做的一切准备给我留下了极其深刻的印象。
B So am I. New roads, new metro lines, new sports centres - there's so much going on.
B 我也是。新的道路，新的地铁线，新的体育中心——这么多的东西都在建设中。
A I'm sure they'll be really successful.
A 我肯定它们将非常成功。
B I'm sure they will. The organisation seems excellent.
B 我肯定它们会的。组织工作看起来非常有序。

Notes注释
1 If you believe something will happen, you can say: I'm sure / I'm sure. For instance, talking about the Olympics: I'm sure they'll be really successful. / I'm sure they'll be really successful.
如果你相信某事将会发生，你可以说：I'm sure /我肯定。例如，谈论奥运会时说：I'm sure they'll be really successful. /我肯定它们会非常成功。
2 If you think something is being done very well, you can say you are very impressed / very impressed, e.g. I'm very impressed with all the preparations. / I'm very impressed with all the preparations.
如果你认为某事进行顺利，你可以说very impressed /给你留下了非常深刻的印象，例如：I'm very impressed with all the preparations. /所有的准备工作都给我留下了极其深刻的印象。
3 Another way of stating your impressions is to say: It seems / It seems. Again, talking about the organisation of the Olympics: The organisation seems excellent. / The organisation seems excellent.
另一种陈述你的印象的说法是：It seems /看起来。再一次谈论奥运会的组织工作：The organisation seems excellent. /组织工作看起来非常出色。

Key phrases and sentences
I'm very impressed with all the preparations for the Olympics.
So am I. New roads, new metro lines, new sports centres - there's so much going on.
I'm sure they'll be really successful.
I'm sure they will.
The organisation seems excellent.

对奥运会的召开所做的一切准备给我留下了极其深刻的印象。
我也是。
新的道路，新的地铁线，新的体育中心——这么多的东西都在建设中。
我肯定它们将非常成功。
我肯定它们会的。
组织工作看起来非常出色。