Go Banana = becomes crazy; Go Toilet ???

"to" gives readers a sense of action done towards a place. Here, "go" is an intransitive verb (i.e. no object; nothing to accept/receive the action). One can make a toilet, break a toilet, flush the toilet (all transitive verbs) but 'go a toilet' doesn't make any sense. So one has to say "I go to school by bus."

Another meaning of "go" is "to be". For example: "go bananas" means "go crazy", i.e. to become crazy. I don't think your teachers would want to know if you want to be a toilet.

Sometimes, we go shopping, we go swimming ... Here, shopping and swimming are activities. Toilet is a thing. So you should say "Teacher, may I go wee wee/poo poo?" which is like in Chinese 先生, 我想痾屎!  

http://dictionary.cambridge.org/dictionary/british/go_1
http://dictionary.cambridge.org/dictionary/british/to_2
http://dictionary.cambridge.org/dictionary/british/to_3

Sleep vs. Nap; Name vs. Lamb

Are You Finished?

I tend to ask students if they 'are finished'. But they laugh as if I'm asking if they're dead.

http://www.bbc.co.uk/worldservice/learningenglish/language/askaboutenglish/2009/06/091006_aae_finished.shtml

Alternatives:

Are you done?

Are you through?

環保－－可能嗎？

最唔環保就係「人」。想環保只有優化人嘅素質，勿過份生育。但系因為人權嘅問題，咁系冇可能。雖然中國嘅 one child policy 產生咗好多問題，但如果當初無推行嘅話，今日會有更多及更嚴重嘅問題。當然從教育入手亦可以，但系要點樣餒當咁教育到每一個人亦系好大嘅問題。教育咗亦未 必從此就冇人唔貪方便、唔自私。10 個環保人都唔知保唔保救到 1 個唔環保嘅人嘅破壞力。地球有セ嘢未試過？冰河時期、大爆炸...... 救地球？救救你自已先啦！好好做個環保嘅家長啦。

To or not to. That's the questions.

Student's sentence: "We should help our parents to clean the house." Her teacher crossed her 'to'. "To or not to. That's the question."

http://www.bbc.co.uk/worldservice/learningenglish/grammar/learnit/learnitv226.shtml

Here Comes the Tenses! - 6 Present Perfect

• about a period of time which is continuing; for unfinished actions and events; time stated is not finished (with since, for, still, yet)
  I've practised my piano since 4 o'clock. (it's 4:15)
  I've lived there for 4 years. (still living there)
  I still haven't finished my homework.
  Mum hasn't prepared dinner yet.
  The builder have started working on the kitchen this week.
  

• express recent event (often with just); to focus on the results of an activity or event which is complete
  Jack has just been to the bank.
  I've mentioned the car. (= I've just finished so we can go out in it now)
  

• unspecified past even or time is irrelevant; talk about how many times something has happened (with adverbs like already, before, ever and never; after a superlative)
  I've lost my new camera. (it's irrelevant when)
  Pete has been to New York 3 times.
  I've met her before somewhere.
  It's the biggest dog I've seen.

Diary of Wimpy Kid (1)

The first Wimpy Kid can be read online for FREE!!

http://www.funbrain.com/journal/Journal.html?ThisJournalDay=1&ThisPage=1

Here Comes the Tenses! - 3 Present Continuous

• present moment; temporary action with now, at the moment, at present, or just
  I'm wearing a pair of old jeans.They're eating lunch at the moment.
  

• current projectWe're working on our geography project this month. 
  

• changing or developing situations with always or continually
  You're always buying new video games! (you buy too many)
  
• unexpected things happens several times
  I'm always meeting my neighbour John near the station.
  
• arranged plansJanice is meeting Frank tomorrow at 2 in the coffee shop.
  
  
  

Here Comes the Tenses! - 2 Simple Present

• happen regularly & habits
  Jason takes the bus to work every day.
  
• general truth
  The moon goes round the earth.
  
• permanent situations
  I work in Central.
  
• to describe the plots of books and films
  The story begins and ends in Spain. The year is 1937.
  
• for scheduled events with a future meaning
  timetables - My plane arrives Hong Kong on Saturday at 14:30.
  programmes - The meeting starts on Wednesday at 9:30.
  plans - The speaker arrives on Tuesday afternoon.

Here Comes the Tenses! - 5 Past Continuous

• for interrupted action
  They were eating dinner when he arrived home
  
  
  
• 2 things happening at the same time
  He was buying a burger and all the crowds were walking past.
  
  
  
• for exact time in the past
  I was reading last night at 9:30 p.m.