The research is so designed that once _____ nothing can be done to change it.A beginsB having begunC beginingD begun_____ in thought,he almost ran into the car in front of him.A LosingB Having lostC LostD To loseIf you go to Xi'an,you will find the palaces there more magnificent than commonly _____A supposingB supposedC to supposeD supposeJane and John still remember that it was _____,their parents,who encouraged them to continue the educationA whoseB

D
C
B
C
D

1.D so...that 连用 ONCE BEGUN 是省略句
2.C Lost in thought是陷入沉思。一般用来作状语 你就这样记住就好啦
3.B 与 magnificent 并列，它是形容词 所以用 supposed
过去分词做形容词
4.C 是强调句 IT WAS....THAT/WHO .....人的时候任选一个
物的话只能用 THAT
5。B到明年的那个时候，你将已经有800个词汇量
是将来完成时

1.D once后省略了it is,补充完整应该是The research is so designed that once it is _____ nothing can be done to change it.这样可以明显地看出it指代The research,与begin构成被动关系,故选D.
2.C be lost in thought 这是一个固定表达,意为“陷入沉思”.而该题中用作状语,仅保留过去分词即可.
3.B 该句意为“如果你去西安,你会发现那里的宫殿比人们通常认为的更有意义”.宫殿与suppose构成被动关系,即人认为宫殿有意义,宫殿被认为有意义.
4.C ...it was _____,their parents,who ...这是一个强调句型,强调主语,只不过被强调的部分they,their parents是一个同位语.
5.B By this time next year这一时间状语提示我们应该用将来完成式“will have done” .

d虚拟语气，时态退后c介词短语作状语be lost in thought 陷入沉思 b想像是过去的动作，用过去式 d 蒙的 b 这是将来时，截止时间是将来，而且对于将来来说，你那是已经掌握了800个单词了，所以用将来完成时。