Question

all but Tom后面的动词的单复数根据什么来定

Answer 1

have.

all but 有 “除了.都.”的意思 除了汤姆,大家都有.

同理的句子：

All but the morning star have disappeared.

除掉金星以外其他的星星全都消失了

All but my auntie have had lunch.

除了我的婶婶以外,大家都吃了中饭了