Breakdown of Suppongo che l'ispettore indaghi sul crimine.
sul
on the; about the (su + il)
l'ispettore
the inspector (m)
indagare
to investigate
il crimine
the crime
Questions & Answers about Suppongo che l'ispettore indaghi sul crimine.
Why is the verb "indaghi" and not "indaga"?
Because the sentence starts with suppongo che (I suppose that). Verbs expressing opinion, belief, or doubt like supporre (to suppose), credere, and pensare trigger the subjunctive mood in the following clause. Therefore, we use the present subjunctive indaghi instead of the normal present tense indaga.
Why is there an "h" in "indaghi"?
The infinitive is indagare. To form the present subjunctive for -are verbs, we drop the ending and add -i to the stem. However, if we just wrote "indagi", the pronunciation of the "g" would change to a soft sound. We must add an h to keep the hard "g" sound from the infinitive, making it indaghi.
Why do we say "indaghi sul crimine" instead of just "indaghi il crimine"?
In Italian, the verb indagare (to investigate) is almost always followed by the preposition su (on/about) when specifying what is being investigated. Here, su combines with the definite article il to create the articulated preposition sul.
What is the infinitive of "suppongo" and how does it conjugate?