Is there any grammatical rule to know which verbs can (or better, must) be sometimes followed by "to"? Some examples are:
I'm aware I could also say "explain me", but such thing would mean something like "explain what I am" or "give an explanation of myself". However, you could never use "say me". In other cases, it seems both formats are acceptable. An example would be:
Is there any rule to explain this?
Because underneath it all, the word meant to flatten {something} out and that meaning acquired a figurative meaning "to make clear, easily understood"; the sense that it is a figurative use has been lost with time.
The direct object of "explain" is thus the thing being explained, not the person to whom the explanation is being given.
English is a Germanic-Latinate hybrid.
According to George Yule, "[w]ith verbs such as describe or explain, we put indirect object after a preposition, not after the verb"
She described the thief to the police.
They explained the plan to us.
Other verbs which fall in this category are admit, announce, mention, murmer, report, shout, suggest, and whisper.
You see they are often verbs of speaking.
She said "Hello" to me. (NOT she said me "Hello".)
book, buy, get, cook, keep, bring, make, pour, save, find, give, lend, offer, pass, post, read, sell, send, show, promise, tell
With these verbs, a noun or pronoun right after them has something like an implied "to" or "for" in front of it - it's built-in to the meaning of the verb. (Except keep - e.g. keep me in the loop no preposition works).
Any other verb, you need the "to" or "for" explicitly expressed.
The normal verb construction is "Can you get me a newspaper?"
Another type is "Can you explain this sentence to me?".
Type 2 is mostly used with Latin verbs such as
announce confide deliver demonstrate describe dictate distribute entrust explain introduce prefer propose relate suggest (this is only a selection). Also to say, which is no Latin verb.
I can't give a simple and clear reason why we have two types. Type 1 might be a simplification of type 2, but was used only with frequent Germanic verbs. But this is a mere guess.
What an interesting question! I can only add this: be literal. In your example,' "Show me" and "show it to me" ', it is worth noting that "show me" is a common-usage abbreviation for the longer "show it to me". With this in mind, when you want to express a thought, in written form, be literal. Expand your wording to include everything you think is necessary to convey your point. Let's go back to the "Show me" example. Some languages will assume the "to". English does not. Therefore, one can not go wrong by using the extra word, "to".
