They are compound words
Most characters have multiple meanings, in many cases an individual character in a compound word can also be a short form for another word
"天真" is combination of two adjectives
天 means 天然 (natural)
真 is short for 純真 (pure/ innocent)
"天真" = natural + innocent = naive
As for "馬上", it is a combination of a noun and a ...
进 can be both verb or directional complement. It can be a verb if it's used alone. for example, if we say "我们进了一幢楼房", it means "we walked into the building".
But when it's used right after another verb, it's a directional complement, and it's used to clarify the direction of the verb in front of it. In the sentence "we move in the building", 搬 corresponds ...
The “进” part is called directional complement.
Rather simply, as we do in English, you can add a directional word to the verb, to describe where the verb is going. The most common words to indicate a direction are:
上, up and 下, down <== notice how they kind of look like arrows?
进, in and 出, out
过, to cross over
回 to come back.
Quote:- "...only 搬 is the verb in the sentence ‘我们搬进了一幢楼房’，but not ‘进’，what is the role of ‘进’ in the sentence?
搬进, (move in), is a "compound verb" -- i.e. a verb that is made up of multiple words.
In English, you have "I believe in you"; "His car swerved and tumbled over", "You need to work on your Chinese", :)
So, without the 进, your sentence would ...