yesterday it was too rainy I_______ go home 空是had to 还是must must不可以用过去吗

应用had to,因为must是一个情态动词,没有过去时和三单形式,但 have to都 有.
例如,
She has to attend the meeting to listen to his report.这里的has to可直接换成 must.意思是她必须参加这个会议去听他的报告.[以后不懂的可以问我.]

had to