They could do nothing but ___ (wait) at home什么时态

They could do nothing but ___ (wait) at home
什么时态

应该是wait
你可以这样理解,but是一个连词,它前面和后面连接的词的词性当然要一致,而前面的动词因为有could要用动词原形,所以后面的动词也当然要用动词原形.
也就是They could (just) wait at home的意思

waiting