The laburnums weren't working
The only concrete noun in your sentence is sentence. Note: The noun 'sentence' is a concrete noun only for a written or spoken sentence; the noun 'sentence' as a word for a penalty imposed for a crime conviction is an abstract noun.
With the exception of not capitalizing the 'y' at the start of the sentence, it is a correct sentence.
The first noun in a sentence may be the subject of the sentence, but NOT ALWAYS, for example:John sat on the bench. (the noun 'John' is the subject of the sentence)He sat on the bench. (the pronoun 'he' is the subject of the sentence, the first noun in the sentence is 'bench', the object of the preposition 'on')
Which sentence sounds the strongest?
When it is at the start of a sentence.
Laburnum is a genus of flowering plants in the legume family, Fabaceae, often known as golden chain trees. They are native to Europe and Asia and are characterized by their striking, pendulous clusters of yellow flowers that bloom in late spring to early summer. While beautiful, all parts of the laburnum plant are toxic if ingested, containing alkaloids that can be harmful to humans and animals. Laburnums are commonly used in ornamental landscaping for their aesthetic appeal.
It is the first sentence of a paragraph which is the topic sentence.
It in symmetry with sentence a is what? What is a sentence with symmetry in it? This sentence with symmetry is symmetry with sentence this.
Who or what the sentence is about is the subject of the sentence.
Who or what the sentence is about is the subject of the sentence.
The subject of a sentence is who or what that sentence is about.
yes
the meaning of sentence is sentence
A subject in a sentence is who, what, or where the sentence is about.
As a question, it can be a sentence, like: A sentence can have one word, and as a question then it can be a sentence: Who?
compound sentence, simple sentence, and complex sentence
a descriptive sentence is a sentence that describes something in one sentence