necessity

1.the necessity后面接of或for和动名词比接不定式普通，如the necessity of（或for）doing this比the necessity to do this普通。但There is no necessity，under no necessity，under a necessity和under any necessity后面接不定式。例如：

• There is no necessity (for me) to do this.
• He is under no necessity to do this.
• He is under a necessity to do this.
• I do not think he is under any necessity to do this.

跟There is no necessity相仿的有Is there any necessity...和Where is the necessity...? 后面接不定式或of和动名词都可以。例如：

• Is there any necessity (for him) to do this?
• Is there any necessity of (his) doing this?
• Where is the necessity (for him) to do this?
• Where is the necessity of (his) doing this?

2.the necessity和a necessity后面接for和名词比接of和名词普通，如the（或a）necessity for a trip to the North和the（或a）necessity for incessant watchfulness比the（或a）necessity of a trip to the North和the（或a）necessity of incessant watchfulness普通。

3.Such a step involves the necessity of the Minister himself being present里的involves the necessity of作“势必需要”解，是公文用语。这句可以改作Such a step requires the Minister to be present或necessitates the Minister's presence。

4.参见necessary 4