The blanks in the partial words below can be filled in with letters to complete the words - according to a certain pattern. What is the pattern and what are the new words.

1.   _ N _ T _ A L

2 . _ D _ R _ U S 

3.  _ N _ S _ A L

4. _ L _ M _ N T

HINT:

_ D _ M _ N T could be added to the list.

Answer:

Each partial word can be completed by placing the same vowel on each blank. (Each word uses a different vowel.)

1) I:  I-N-I-T-I-A-L 

2) O: O-D-O-R-O-U-S

3) U: U-N-U-S-U-A-L

4) E: E-L-E-M-E-N-T

HINT:

A: A-D-A-M-A-N-T