He must have had an accident,or he then.A.would have been hereB.had to be hereC.should be hereD.would be here请老师详细讲解这道题，为什么选A项而不能选其他项啊？这个题中then的作用是什么啊？then的用法有哪些啊？谢谢老师啦。
比如：appear to be/to be doing/to have done和appear to do，前面的appear是系动词嘛？apper to do这里是半助动词还是系动词？如何区分半助动词和系动词呢？比如 be going to/be about to do等这些都是助动词，都是接to 的不定式，为什么这些不能接...
... several local geological journals in the 20th century.
请问这句话中的first by national journals in the 19th century and then by several local geological journals in the 20th century.修饰refereeing【推荐制度】应该怎么翻译，这里的by的意思是什么
Ebenezer Scrooge dismisses a ghostly encounter（as being just as likely from） the crumb of cheese he had before bed埃比尼泽·斯克鲁奇在遇见鬼魂后不以为然，认为是他睡觉前吃的奶酪碎屑在作祟---请教括号内的内容如何理解？
海明威《乞力马扎罗的雪》：He looked over to where the huge, filthy birds sat, their naked heads sunk in the hunched feathers. A fourth planed down, to run quick-legged and then waddle slowly toward the others.请问此处的不定式to do结构在句子里做什么成份？
这个学校的学生比阳光中学少。The number of the students in this school_____ _____ _____ ______ _________ _______in Sunshine Middle School.这里六个空，答案是is smaller than that of those老师能解释下为什么这么填，这个s...