Could someone explain the grammar to me - use of "be changed" in The report recommends that radar screens be changed. Why it is used like this? What does this usage should express? Where (under what name)I could study it in detail? Thank you in advance. Edi
This is an example of writing in the 'third person' - i.e. the subject is always 'he', 'she' or 'it'. It is commonly used in formal or technical reports that will be read more widely than a specific person. In the UK, we use the style to avoid confronting others - in this example we would never say 'you should change the radar screens' since it might confer an element of blame that they hadn't already done so.
This is the subjunctive. According to Wikipedia:
The subjunctive in English is used to form sentences that do not describe known objective facts. These include statements about one's state of mind, such as opinion, belief, purpose, intention, or desire.
While it's sometimes hard to know the subjunctive is being used, this isn't the case with be:
(that) I be, (that) you be, (that) he be, (that) we be, (that) they be