Learn Portuguese (Portugal): Para a graduação, precisamos de estar concentrados, e nós estamo-lo. - For the grading, we need to be concentrated, and we are.

It replaces the adjective concentrados. This is the neuter predicative clitic o. When you replace a characteristic or state (a predicate adjective or noun) after a linking verb like ser or estar, you always use the invariable neuter o, regardless of the gender or number of the word being replaced.

Why is it spelled estamo-lo instead of estamos-o?

When attaching a clitic pronoun like o to a verb that ends in -s, -z, or -r, you must drop that final consonant and change the pronoun to -lo. Here, estamos drops the final -s and the neuter clitic o becomes -lo, resulting in estamo-lo.

Why do we need the preposition de in precisamos de estar?

In European Portuguese, the verb precisar (to need) generally requires the preposition de before both nouns and infinitive verbs. While you might hear it dropped before an infinitive in very informal speech or in Brazilian Portuguese, precisar de is the standard and expected form in Portugal.

Is it necessary to include the pronoun nós in e nós estamo-lo?