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Which sentence is right?

  • It's important that he should know this.
  • It's important that he shall know this.

Is the shall/should auxiliary or modal verb?

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up vote 2 down vote accepted

You can use one of the following.

It is important (that) he knows this.

It is important (that) he should know this.

It is important (that) he know this. (subjunctive)

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You could also use the subjunctive and say, "It's important he know this." – Tragicomic Jan 19 '11 at 7:25
@Tragicomix: That doesn't sound right... Are you sure? – Guffa Jan 19 '11 at 8:07
@Guffa: Yes. Here's a link to the BBC World Service's Learning English site. I understand that the subjunctive has been falling out of use. It is still a good way to show mood without using a modal auxiliary. bbc.co.uk/worldservice/learningenglish/grammar/learnit/… – Tragicomic Jan 19 '11 at 8:47
@Tragicomic How could I different the subjunctive mood from wrong tense ? – lovespring Jan 19 '11 at 9:15
One comment: In traditional usage, if you say "It is important that he knows this," you are implying that he probably knows it. If you say "It is important that he know this," or "It is important that he should know this," you are implying that there is a good chance that he doesn't already know it. However, with the subjunctive falling out of use, this distinction may not be as clear. – Peter Shor Jul 26 '11 at 20:46

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