up to now只能与现在完成时连用吗?Up to now I have been reading this book

up to now只能与现在完成时连用吗?Up to now I have been reading this book up to now只用于现在完成时吗? I have been up to this you havent been to beijing up to now,have you yes,I havent . 英语翻译Up to now there have been many explanations____the cause up till now 与up to now区别 up till now/up until now/up to now 1.up to now up to now 造句 Up to now, large quantities of food have been sent to Africa To dedicate this book to those,like me,have been or are now by now.until now.so far.up to now.till now.是不是都可用于现在完成时的未完成用