A new law <em>must be passed </em>before tomorrow. The complete verb phrase is <em>must be passed</em>. The main verb is <em>pass</em> in the past: <em>passed</em>. Then, there are two aulixiaries: <em> must</em> , which indicates moral obligation and<em> be </em> which indicates passive voice. This means that a law must be passed by an institution such as Parliament or Congress.