Semi-composite sentences, also known as complex sentences, are a type of sentence that contains both independent and dependent clauses. These clauses are connected to each other and contribute to the overall meaning of the sentence. In the examples given, there are several types of semi-composite sentences: 1. "She was heard to play the piano." - This sentence contains a dependent clause ("She was heard") and an infinitive phrase ("to play the piano"). The infinitive phrase acts as the direct object of the verb "heard" and adds additional information about what she was heard doing. 2. "I insist on your coming to the meeting on Saturday at 10 o'clock sharp." - This sentence contains a dependent clause ("I insist") and a gerund phrase ("your coming"). The gerund phrase acts as the direct object of the verb "insist" and adds information about what the speaker is insisting on. 3. "Unfortunately, at that moment George was overcome with this emotion and lost his nerve." - This sentence contains a dependent clause ("Unfortunately"), an independent clause ("George was overcome with this emotion"), and another independent clause ("lost his nerve"). The dependent clause sets the tone of the sentence and adds additional information, while the independent clauses provide the main actions and events of the sentence. 4. "Famous inventors and scientists gathered in the assembly hall of the Zoological Institute." - This sentence contains an independent clause ("Famous inventors and scientists gathered") and a prepositional phrase ("in the assembly hall of the Zoological Institute"). The prepositional phrase adds additional information about where the gathering took place. 5. "We heard some noise coming from the room upstairs." - This sentence contains an independent clause ("We heard") and a participle phrase ("some noise coming from the room upstairs"). The participle phrase acts as the direct object of the verb "heard" and adds additional information about what was heard. 6. "The letter being written, he went to the post-office to drop it into the mail-box." - This sentence contains a dependent clause ("The letter being written") and an independent clause ("he went to the post-office to drop it into the mail-box"). The dependent clause sets the context for the main action of the sentence, which is stated in the independent clause. These examples demonstrate the different ways in which semi-composite sentences can be constructed using various types of phrases and clauses. The combination of dependent and independent clauses allows for more complex and nuanced expressions of ideas.