This is often for great helpful to the police.这句话正确吗?

it often have great help to the police

be of help= be helpful
同样 类似的还有be of great importance = be very important

this is very helpful in the police

this is often a great help to the police

二楼的好像对，
This is often of great help to the police.

不正确,This is very helpful in the police .

This is often for great helpful to the police.
是 This is often of great help to the police.

您没说明本来想表达的意识是什么，怎么改正？