Greeting:
Thank you all for being here.
谢谢各位的到来。
I want to thank you all for attending this… .
我想谢谢各位愿意前来参加这场…
I'd like to thank you for coming.
我想要谢谢你们的到来。
It's a pleasure / an honor for me to be here.
能够站在这里是我的一大荣幸。
I'm very happy to have this opportunity to… .
我很高兴能有这个机会来…
Good morning. Thank you all for being here. I'm very glad to have this opportunity to share my thoughts about environmental pollution with you.
早上好，谢谢各位的到来。我很高兴能有这个机会来跟大家分享我对环境污染的看法。

Techniques:
There are… main aspects to this topic.
关于这个主题，大致可以从...个角度切入。
I've divided my speech / presentation into… parts.
我的演讲／报告将会分成...个部分。
I'm going to start with… , and then talk about… .
我会先从...开始，然后谈论…

Ending:
Thank you for listening, and I hope you enjoyed my… .
谢谢各位的聆听，希望你们享受我的...
This is the end of my… , and thank you for your attention.
我的…到此结束，谢谢大家。
I appreciate the time you took to listen to my… , thank you so much.
我很感谢各位拨冗聆听我的…，谢谢你们。
This is the end of my presentation. Thank you for listening, and I hope you all enjoyed my talk about environmental pollution.
我的陈述到此结束。谢谢各位的聆听，希望你们有享受我关于全球暖化的谈话。