Answer:
Idiom is the grammatical name for the expression used.
Explanation:
An idiom is figurative sentence which provides variety in presenting the ideas and tends to awaken the senses of the readers. 
The expression "Shocked to the marrow with fear" explains how deeply one is shocked with the fear. 
Hope than answers your question. 
 
        
             
        
        
        
By using past and present tense
        
             
        
        
        
"The longer the board, the more power one had"
        
             
        
        
        
Answer:
a. A very young child; an infant.
b. An unborn child; a fetus.
c. The youngest member of a family or group.
d. A very young animal.
2. An adult or young person who behaves in an infantile way.
3. Informal
a. A lover or sweetheart.
b. Sweetheart; dear. Used as a term of endearment.
4. Slang An object of personal concern or interest: Keeping the boat in good repair is your baby.
adj. bab·i·er, bab·i·est
1. Of or having to do with a baby.
2. Infantile or childish.
3. Small in comparison with others of the same kind: baby vegetables.
tr.v. ba·bied, ba·by·ing, ba·bies