It is (a)___ that the new century is now facing various challenges specialty environment (b)___. Feeding the ever growing population is (c ) ____ first and foremost challenge for Bangladesh. It is very difficult to (d)___ the current level of agricultural production. Because our agricultural land is being reduced due (e)___ Human habitat , industrialization  , river (f)___ etc. Beside we are losing our forests gradually. Trees are being cut down (g)___ resulting in (h)___ increase of pollution. So it is (i)___ to check the reckless alarming condition (j)___ our own existence.

We are not ungrateful to the freedom fighters.

Their contribution is the greatest thing. 

An imperative sentence expresses a command, request, advice, or suggestion. It typically starts with a base form of a verb, and the subject 'you' is often understood but not stated. To form a negative imperative, 'Do not' or 'Never' is placed at the beginning of the sentence.

In the given sentence, "You should never disrespect or forget our martyrs," 'should never' indicates a strong suggestion or advice against an action. To transform this into an imperative sentence, we remove the implied subject 'you' and the auxiliary 'should', directly starting with 'Never' to convey the strong negative command or advice.

Our government has built the national memorial with a view to paying tribute to their memories. 

 (e) A freedom fighter is greater than any other son of the soil.

Our independence was got/gotten by us for their sacrifice.