句子My friends and I think it must be teenagers having fun.中 为

but my friends and i think it must be teenagers having fun为什 I think it must be teenagers having fun.这句话的句子结构是怎样的 It must be teenagers having fun 为什么这里要用having而不用to have it must be teenagers ------------fun.A have B having C had D That must be teenagers having fun noise 语法错误吗 It must be teenages having fun 这里为什么要用having 而不用to have I think it must be的意思 帮忙纠正英语句子1.I think my life in ten year swill be fun My friends and I have fun singing our f___songs. I think my winter holiday will be very fun i think that we must be talking about it in private 这个句子错了吗? 翻译 I think it would be kind of fun.