4) It is essential that the increase in production should be geared to (适应) the increase in public demand.
5) It is necessary that young and old people should communicate more with each other.
6) It is thoughtless of some parents to allow their children to watch whatever program is on television.
7) It is incredible(不可思议) that he ate the big cake just in tow bites.
8) It was obvious to everyone that the marriage would sooner or later end in separation if not diverce.
9) It was clear that Dad could do no more than he was doing already.
10) It is certain that fresh air and exercises are more valuable than medicine.
