1. a) yes b) no In British English we can say 'in hospital', but not 'at hospital'. In British English you can say either: 1 a) I am visiting a friend at the hospital. If you say this, it probably means that there is only one hospital in your town or neighbourhood, and that the listener knows that you are talking about this one specific hospital. 1 b) I am visiting a friend in hospital. If you say this we don't know which hospital your friend is in. It could be any hospital. 2a) I go to the barn and collect the eggs. b) I go to the barn and collect eggs. Both of these are correct, but - again - the meaning is slightly different. As @Certainly says, if you say 'the eggs' , the listener knows which eggs you are talking about. In both cases, the use of 'the' makes the noun specific, and it is understood that the listener knows which hospital or which eggs you are referring to.

American English requires "the" before "hospital" in your example. British English does not. Both of your egg-collecting sentences are acceptable, but the first one sounds more natural.

For the first two sentences, only sentence "a" is correct. You must use the article "the" before the noun "hospital". For the second two sentences, both require an auxillary verb, but other than that are correct. Each sentence, however, carries a slightly different meaning. "I will go to the barn and collect the eggs" means that you are collecting a specific group of eggs "I will go to the barn and collect eggs" means that you are collecting whichever eggs you find Hope this helped :)

1. I am visiting a friend at the hospital. 2. I go to the barn and collect eggs.

a,b