MISSING LINK CXXXVII

Each trio of words below shares a Missing Link - that is, its members have something in common, obvious or not. For example, RIVERS, NOSES, & VIOLINS can all have BRIDGES.

1. Pin..........Easy..........Seed
2. Bar..........Cadet..........Junk
3. Force..........String..........Man
4. Circus..........Trees..........Married people
5. Beauty..........Rose..........Fairy
6. Twins..........Lion..........Bull
7. Canyon..........Spring..........Turtle
8. West..........Grade..........Turning
9. Chain..........Block..........Open
10. Adam..........Abraham..........Euclid

Answers:

1. Kinds of money
2. Space
3. G - 
4. They all have rings
5. Queen
6. Symbols of signs of the Zodiac 
7. Box
8. Point
9. Letter
10. Fathers
    (Adam - father of men)
    (Abraham - father of nations)
    (Euclid - father of geometry)