This dictionary is considered _____ a great help to students of English.A to be B being 为什么

this is a dictionary( )you This is his dictionary同义 This is his dictionary(一般疑问句) this dictionary is in that box复数 Is this your dictionary?改为肯定句 This is his dictionary(改为一般疑问句) This is my dictionary.改为疑问句 This is a dictionary (作否定回答 Is,this,your,dictionary?(改陈述) Is this your dictionary肯定回答 This is my dictionary做否定形式 This dictionary is w______ five yuan. Is this her dictionary?(作肯定回答) ______ a dictionary in English.A.It's B.That C.this is D.My This is a ( ) English-chinese dictionary.A.worth B.worthy C.worthwhile [ ]This is _____ dictionary._____is over there.A.my；Yours B.yours;Mine C.my;Your This is not my dictionary.It's______A.your B.you C.her D.hers This is ___ useful dictionary .选择：A.an B.a C.the D./