"Switch it off" is what we say in America.
It could be construed as grammatically correct, with the following meaning: "You heard (that) the alarm goes off [every morning]." (Imagine, for example, a judge at a trial, summarising the evidence that has been presented in a murder trial.) However, taking it as it stands, as a complete sentence, it is incorrect. The following are correct versions (all with slightly different meanings): "You heard the alarm go off." "You heard the alarm going off." "You heard (that) the alarm went off."
Arrived exactly at their cut off time is not correct grammar. It is a sentence fragment.A grammatically correct sentence would be, "They [or "The widgets we needed to complete the oscillating framizam" or whatever] arrived exactly at their cutoff [not cut off] time."
No, the correct phrasing would be "Where was I?" to form a complete and grammatically correct question.
switched-off i believe
Neither of these are complete sentences. The latter may be used as part of a sentence: 'He is afraid of the letter sending off a bad impression.' but this would be better: 'He is afraid the the letter will send off a bad impression.'
Not technically: the compound subject uses the plural verb are."There are a spoon and a fork on the plate."But colloquially this construction, while erroneous, is very common. It could also be grammatically correct if the spoon is not on the plate (set off by a comma)."There is a spoon, and a fork on the plate." (and there is a fork on the plate)
the correct way to say it is both of them cause they both make sense...
(this should be a grammar question) Switch off the light(s).
The phrase "head off to meet with somebody" is grammatically correct. It means to begin the journey to meet someone.
the switch of the stove turned off.
"Off you go" is not grammatically incorrect.
Nooo...