Explanation: We use Present Perfect Continuous (has/have been + verb-ing) for actions that started in the past and continue until now, especially with time expressions like "since" or "for".
Show/Hide Explanation
1. You _____ wear a seatbelt when driving. It's the law.
Explanation: "Must" expresses strong obligation or necessity, especially for laws and rules. "Should" is for recommendations, "might" for possibility, and "could" for ability or possibility.
Show/Hide Explanation
1. If I _____ (have) more time yesterday, I _____ (finish) the project.
Explanation: This is a third conditional sentence (impossible past situation). We use "If + past perfect" in the if-clause and "would have + past participle" in the main clause.