There remain several questions still to be answered.
Suddenly there was a loud explosion.
They were all laughing when there came a knock at the door.
GRAMMAR GRAMMAR Use there is/are to say that something exists or happens• There was an argument. • Is there any more bread?• There is one thing I'd like to ask you (NOT Is one thing ...).When the following noun is plural, use there are/were• There are a lot of problems (NOT there is a lot of problems) with this theory. • Were there many people at the meeting? !! Expressions like a lot ofandplenty of can be used with uncountable nouns. In this case use there is/was• There is a lot of traffic in the mornings.!! There and their sound the same, but do not confuse them. Thereis used in expressions such as 'there is/was', and for referring to a place. Their is used for showing that something belongs to a group of people, animals etc• They love their jobs.
Definition from the Longman Dictionary of Contemporary English Advanced Learner's Dictionary.