"He is probably going to come."
Translation:Il va sûrement venir.
Despite the fact that "sûrement" comes from "sûr" which is the French for "sure" or "certain", it can mean "surely" and "probably". In fact, in most cases it will mean "probablement". For instance here if you say to a Frenchman "Il va sûrement venir" he will understand that it is not a 100% sure that he will come. It's weird but it's like that and I have no idea why it became like this. If you are sure that he will come then simply say "Il va venir".
yes, it is a rule, you cannot place an adverb in front of a verb in its simple form.
- il viendra probablement
but, you can place it differently if the verb is conjugated in a compound tense or used with a modal verb, like:
- il va probablement venir
- il peut probablement venir
- il est probablement venu
- il était probablement venu
He is going to + verb = il va + infinitive verb: this is near future, constructed in both languages with verb "go/aller".
Two differences with English,
use of English continuous present tense (be + Verb-ing) vs French simple present tense (continuous tenses do not exist in French).
French verb aller is constructed (like a modal verb) without a preposition: aller + infinitive, vs go to + verb.
When it comes to the adverb "sans doute/sûrement/certainement", its placement is preferable after the verb it modifies: il va sans doute venir.