形容词:important, necessary, urgent, essential, vital, natural, strange, proper等
动词的-ed形式:arranged, suggested, ordered, required, desired, demanded, proposed等
It is necessary that the program (should) be loaded into the computer.有必要把程序输入电脑。
It is strange that he should have learned so much in such a short time.很奇怪他竟然在如此短的时间内学了那么多的东西。
It is desired that we (should) get everything ready by tonight.希望一切在今晚前准备就绪。