我需要去趙洗手间。
A: Would you mind I leave for a moment? I need to go somewhere.
您介意我离开一会儿吗？我需要去趟洗手间。
B: Go ahead.
请便！
第二句：I want to wash my hands.
我想去趟洗手间
A: Excuse me. I want to wash my hands.
对不起，我想去趟洗手间。
B: As you like.
请便！
其他表达法：
Where can I wash my hands?
请问洗手间在哪里？
Could you tell me where I can wash my hands?
请问洗手间怎么走？