請幫我改這幾句英文

Does it has one toilet?
這兒是否得一個洗手間呀?
Is there only one toilet here?
(you need HERE because you said 這兒, and you need ONLY because you said 得)

Did you have a cup of coffee today?
你今日飲左咖啡未呀?
Have you had your daily cup of coffee yet?
(I assume that when you say that sentence you mean the 'YOU' drinks coffee everyday)

When do you have a vacation?
你什麼時候有大假呀?
When will you have your vacation?
(future tense because the 'YOU' isn't going to have the vacation NOW, as in present tense)

Your mother found you just now.
你媽媽剛剛找過你
You mother was looking for you just now.
(found means your mum saw you, and not just looking for you)

If you have free time,we can have dinner.
如果有時間,我們可以一起吃飯.
We can have dinner together if you have free time OR
If you have free time, we can have dinner together.
(the emphasis is to add the TOGETHER because 'we can have dinner' is always true, that everyone can have dinner. But here what you want to say is that to have dinner TOGETHER)

my mother is drinking a cup of coffee everyday

你咁口語化的句子給你一點地道外國人的講法吧
註按你中文的用意

Does it has one toilet?
這兒是否得一個洗手間呀?
Isn't there another toilet here?
英文常會用反轉問法的:)

Did you have a cup of coffee today?
你今日飲左咖啡未呀?
Have you had your coffee today?
Have you had your daily coffee fix?

When do you have a vacation?
你什麼時候有大假呀?
When will you take your vacation(annual leave).

Your mother found you just now.
你媽媽剛剛找過你
Your mum just came by looking for you.

If you have free time,we can have dinner.
如果有時間,我們可以一起吃飯.
We could have dinner if you are free.
這句你必須表明處境才有得寫，不過這是最簡短的提問。用could已表白是一個假設意向的問題，if you are free表明是現在（今晚），如果你是想說另一晚則用其他人的回答會比較formal.

Does it has one toilet? (Is there only one toilet here?)
這兒是否得一個洗手間呀?

Did you have a cup of coffee today? (Have you had you coffee today?)
你今日飲左咖啡未呀?

When do you have a vacation? (When do you have your vacation?)
你什麼時候有大假呀?

Your mother found you just now. (You mother has been looking for you)
你媽媽剛剛找過你

If you have free time,we can have dinner. (If you are free, let us have dinner together)
如果有時間,我們可以一起吃飯.