题目内容：

1.Research___all over the world into the possible cause of cancer  in the past years.
A.was made  B.had been made  C.has been making  D.has been made
2.Fibers of hair and wool are not continuous and must normally be spun into thread___woven into textile fabrics.
A.as are they  B.when to be  C.that they are  D.if they are to be
3.All the tasks____ahead of time,they decided to go on holiday for a week.
A.had been fulfilled  B.having been fulfilled  C.were fulfilled  D.been fulfilled
4.He was ashamed ___to pass the exam.
A.to fail  B.to have failed  C.to be failed  D.to be failing
用括号里给出单词的正确形式填空
_____(see) from the top of the tower,the professor gave us a warm welcome.
_____(finish) the painting,he began to make a frame for it.
_____(face) with difficulties,we must try to over come them.
2题答案是D,
还有填空_Seen____(see) from ..._Faced___(face) with difficulties.....我也很费解。
为什么___Having finished__(finish) the painting.用Having，而__Faced___(face) with difficulties用过去分词，

优质解答

1、D 句中有in the past years 就要用完成时时态,research研究是被人研究,所以要用被动语态,并且在过去几年里,实则是从过去一直到现在的,影响到现在,所以要用现在完成时,因此选择D.2、D 句子的意思是纤维和羊毛是不...