It depends on how it is being used, but the past tense of the verb "to be" would be "been", and the plural form could be either "has been", "were", "was", or "have been".
been.For example the past participle is used in present perfect tense egI have seen the Eiffel Tower. seen is past participleI have been to Paris. been is past participle.
The past tense.
The auxiliary verb "have" creates the perfect tenses and is used with the past participle of a verb. The word not is an adverb used to express the negative. It is used between the auxiliary verb and the verb.Example:Verb take, past tense took, past participle taken -Past Perfect : "He had taken the money from the safe."Past Perfect : "He had not taken the money from the safe."The continuous tenses use the present participle(-ing) form -Past perfect continuous : "He had been taking his medicine."Past perfect continuous : "He had not been taking his medicine."
There's not exactly a past tense for it. You would say it as 'was real', 'had been real', 'used to be real', etc.
Copper and tin
what has sulfur been used in the past?what has sulfur been used in the past?
Tin is used in making the alloy brass, and brass has often been used in making part or all of scientific instruments.
Yes it has been successful in the past
what has sulfur been used in the past?what has sulfur been used in the past?
Have been is present tense and had been is past tense.
Tin has been known for about 5,000 years. The place and person of discovery is not actually known. It has been used for millennia as an alloy to strengthen other metals.
Have been or Has been IS the past participle......it is equivalent to "was".
From Old English tin meaning tin.
Yes it has been successful in the past
Have is used for present and Have been is used for past continous.
Tin can poisoning was from the lead (metal) that used to be used to seal tin cans. It is no longer used.