Please explain the sentence pattern usage of There be

When the noun followed by the verb be is a singular countable noun or an uncountable noun, be should take the singular is; When the noun that follows it is a plural countable noun, be is used in the plural are.

There are example sentences in the sentence pattern as follows:

The verb be in the be sentence pattern can have simple present tense, simple past tense, future tense, and perfect tense.

there isn't harm in trying.Give it a try.

there were fabulous wildflowers in the hills last spring.Last spring, there were some beautiful wildflowers in the mountains.

there will be a fine day tomorrow.Tomorrow will be a sunny day.

Be sentence patterns can be used in conjunction with various auxiliary verbs and modal verbs.

there may be a cigarette in that box.There might have been a cigarette in that box.

there must be some cakes on the table.There must be some cake on the table.

there used to be a hospital there before the war.Before the war, there used to be a hospital there.

Be sentence patterns can also be used in conjunction with predicate verbs such as: be going to, seem to, appear to, used to, be likely to, happen to....But there must be be).

there seem to be a few trees between me and the green.There seemed to be some trees between me and the lawn.

there is going to be a meeting tonight.We have a meeting tonight.

there is likely to be a storm.There may be a torrential rain.

In addition to be, other verbs can also be used in the be structure. For example:

there came a scent of lime-blossom.There was a burst of Bodhi tree dust and fragrance.

once upon a time there lived a king in china.Once upon a time there was a king in China.