英语改错并说明原因Helen left her key in the office,so she had to wait

英语改错并说明原因
Helen left her key in the office,so she had to wait until her husband come home.
改成coming不行?util后面接的是从句?从哪可以看出是个从句?

Helen had left her key in the office,so she had to wait until her husband come(came) home,coming不行,until 后面是一个主谓结构的完整的句子,用 until连接就成了整个的从句