Yes.
The sentence "Whether he was duplicitous regarding his character is open to question" is grammatically correct and complete.
Either one is fine, although each means something slightly different. There is nothing wrong with writing or saying, "The store will be open on Sundays from now on." In that sentence, the word open functions as an adjective. It means not closed, and available to conduct business. If you write, "On Monday, the store will be opened by the assistant manager," the word opened functions as a verb. It means made available to conduct business.
The subject pronoun it will take the place of the subject noun phrase 'the lid of the box': It was left wide open.
An open sentence is an equation that contains one or more variables and letters for the opening to fill in the spaces.
Reopen.
"there come"
No: it requires an object for the verb "open". It would be correct to say something like "We must not open burning packages." Yes, if it means "We must not open (our shop, for example) while it is on fire.
The sentence "Whether he was duplicitous regarding his character is open to question" is grammatically correct and complete.
Yes, of coarse.
No, that sentence is not grammatically correct. Availability is a noun meaning how much of something is there to be used. You could say "What is the availability of this job?" or "Is this job available?" or "Is this job still open?"
I ripped open his shirt to reveal his glorious, sun- tanned abs. Good enough yeah?
After a fire, the owl easily finds food in open areas.
Either one is fine, although each means something slightly different. There is nothing wrong with writing or saying, "The store will be open on Sundays from now on." In that sentence, the word open functions as an adjective. It means not closed, and available to conduct business. If you write, "On Monday, the store will be opened by the assistant manager," the word opened functions as a verb. It means made available to conduct business.
Dial the correct number to open the lock. There is a combination dial on the machine.
No. 'What did you do lately' is correct. The word 'did' puts the verb into the past, and it takes the infinitive form of the verb, not the past tense. 'What song did you sing yesterday?' NOT 'What song did you sang yesterday?' 'What did he eat this morning?' NOT 'What did he ate this morning?' 'Did they open the box?' NOT 'Did they opened the box?'
He has a white shirt on
You need to specify which place you are referring to if you want to make it possible to answer your question. Please, also note that a sentence requires a verb so that a) it is complete grammatically; b) the action which is involved is spelled out.