a) Sentence-a sentence is an expression in natural language, and often defined to indicate a grammatical unit consisting of one or more words that generally bear minimal syntactic relation to the words that precede or follow it. A sentence can include words grouped meaningfully to express a statement, question, exclamation, request or command. A sentence consists of a subject and a predicate.
b) Utterance - An utterance is a complete unit of speech in spoken language. It is generally but not always bounded by silence. It can be represented and delineated in written language in many ways. Note that utterances do not exist in written language, only their representations do.
C) Proposition- the term proposition (from the word "proposal") refers to either the "content" or "meaning" of a meaningful declarative sentence or the pattern of symbols, marks, or sounds that make up a meaningful declarative sentence. The meaning of a proposition includes having the quality or property of being either true or false, and as such propositions are claimed to be truth bearers.
d)interrogative sentence- A sentence that asks a question. (Compare with sentences that make a statement, deliver a command, or express an exclamation.) An interrogative sentence ends with a mark. For example: How are you doing?

e) Declarative sentence- Declarative sentences are commonly used in informal speech to express surprise or ask for verification. The most likely response to a declarative question is agreement or confirmation. For example: Yes, I am.

f) Imperative Sentence: A sentence that gives advice or instructions or that expresses a request or command. (Compare with sentences that make a statement, ask a question, or express an exclamation.) An imperative sentence ends with a period or an exclamation point. For example: “Hello, How are doing?”he said.

1. This pair of sentence expresses the same proposition.
2. This pair of sentence expresses the same proposition
3. This pair of...