1) Derive [A] mineral resources from [B] sedimentary rock [C] is a [D] major modern industrial activity.
2) in the matriculation for postgraduate in a short time is realy a hard nut.
[A] To make high scores[B] To make low goal[C] To the high scores[D] Make the low goals
It is really a hard nut to get high scores in the matriculation for postgraduate in a short time.
3) John admitted that it's always difficult.
[A] for him being on time[B] being on time for him
[C] for him to be on time[D] on time for him
4) It is difficult for me [A] to be concentrating [B] while someone [C] is using [D] a vacuum cleaner.
It took us a great deal of efforts to finish that task.
It made him extremely happy to get contact with his family in Taiwan since they separated more than 40 years ago.
It is quite important for us to read good books during the period of general review(总复习)。
It is not difficult for those who study maths well to pass the exam.
It is very kind of you to help me./It is stupid of him to do such a silly thing.
间或也可用for + there to be 表示(而且there后面的不定式只能是to be)。
It's a great pity for there to be much trouble in the company.