1.Conditional sentence: "If an ad is well-crafted, engaging, and informative, it might be welcomed by audiences even if seen frequently" uses a conditional sentence structure to express a hypothetical situation, demonstrating complex grammar usage.
2.Contrastive conjunction: "However, if it's dull or intrusive, it can quickly become a nuisance" uses the contrastive conjunction "however" to introduce an opposing idea, adding depth and complexity to the response.
3.Infinitive phrase as a noun: "The key is to strike a balance" uses the infinitive phrase "to strike a balance" as a noun, showcasing advanced grammar structures and flexibility in expression.